Correlation of photochemical events with the action potential of the retina

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C o r r e l a t i o n o f P h o to c h e m ic a l E v e n ts w ith th e A c tio n P o t e n t i a l o f th e R e tin a

by V e rn e r Jo h n W ulff

A d i s s e r t a t i o n s u b m itte d i n p a r t i a l f u l f i l l m e n t o f t h e r e q u ire m e n ts f o r t h e d e g re e o f D o cto r o f p h ilo s o p h y , i n th e D epartm ent o f Z oology, i n th e G ra d u a te C o lle g e o f t h e S t a t e U n iv e r s ity o f Iowa J u l y , 1942

P ro Q uest N um ber: 10583665

All rights reserved INFORMATION TO ALL USERS The quality o f this reproduction is d e p e n d e n t upon th e quality of th e c o p y subm itted. In th e unlikely e v e n t th a t th e author did not sen d a c o m p le te m anuscript a n d th ere a re missing p a g e s, th e se will b e n o ted . Also, if m aterial h a d to b e rem o v ed , a n o te will indicate th e deletion.

uest. ProQ uest 10583665 Published by ProQ uest LLC (2017). Copyright of th e Dissertation is held by th e Author. All rights reserved. This work is p ro te c te d against unauthorized copying under Title 17, United States C o d e Microform Edition © ProQ uest LLC. ProQ uest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346

Acknowledgements F o r I n v a lu a b le c r i t i c i s m s , s ti m u l a t i n g d i s c u s s io n and s u g g e s t i o n s , 1 w ish t o convey my a p p r e c i a t i o n b o th t o Dr* T heodore 1 , J a h n and D r# Gordon M arsh

3

T a b le o f C o n te n ts

In tro d u c tio n

6 6

P a r t I - F u n d am e n tals o f th e V is u a l M echanism . . . . . . . . . P a r t XI - q u a n t i t a t i v e A sp e c ts o f th e V is u a l M echanism

. . . .

P a r t I I I - I n t r o d u c t i o n t o E x p e rim e n ta l M a t e r i a l .......................

•

13 15

M a t e r i a l and M e t h o d ................... • « • » » * • • * ...................................................18 R e s u lts and D is c u s s io n « • « • « • • * • • • « « • * » * * * * • * • P a rt I

I n te n s ity - B S F R e la tio n s i n th e D ark-A dapted Eye

P a r t I I - I n t e n s i t y - M F R e la tio n s i n th e L ig h t-A d a p te d Eye

• . •

19

• *

28

P a r t I I I - In te n sity -U M F R e la tio n s f o r B e e tle s P o s s e s s in g a V is u a l D iu r n a l Rhythm • » • • • * • * . » • • » » C o n c lu s io n • • • • « « • • » * * •

19

........................

34 43

Summary

45

B ib lio g ra p h y • • • * • * • • • • • • • • • • • • • • • • • * • • • •

46

4

T a b le o f F ig a r o s 1 . s p e c t r a l a b s o r p t i o n c u rv e f o r S* T y p ic a l e l e c t r o r e t i n o g r a m s

v i s u a l p u r p le

* « • • * • • • • •

8 12

o f In s e c ts * • * * • « • * • * • • *

S« R le c tr o r e tin o g r a m s o f b e e t l e s p o s s e s s in g a v i s u a l d i u r n a l r h y t h m ................................ .......................................................

4 , I n t e n s i t y »M F c o n to u rs f o r t h e d a r k -a d a p te d ey e o f I n s e c t s

17

* .

5 . C o n c e n tr a tio n o f (%) - i n t e n s i t y c o n to u r s • • * * * • # * • * •

20 26

6* Intensity~i& S F c o n to u r s and c o n c e n t r a tio n o f x - i n t e n s i t y con­ t o u r s f o r t h e l i g h t a d a p te d p h o to r e c e p to r « • • • • • • » . . .2 9 7* X n te n a ity -M F c o n to u r s f o r t h e com ponents o f t h e SRC from D y tie c u s * • « « » « *

# 36

8 . In te n slty ~ S M F c o n to u r s f o r t h e com ponents o f t h e ERG from H ydrous * , , * * ..........................

38

5

T a b le o f T a b le s 1* B a ta

p e r t a i n i n g t o c u rv e s o f f i g u r e 4 * *• • • » • • • « • » •

21

2# D ata

p e r ta in in g t o cu rv es o f f ig u r e

2?

3 . D ata

p e r t a i n i n g t o c u rv e s o f f i g u r e

30

4* D a ta

p e r t a i n i n g t o c u rv e s o f f i g u r e 7 * * ,

5* D a ta

p e r t a i n i n g t o c u rv e s o f f i g u r e 6

« * » • * » # • * • «

.

37 39

6 In tro d u c tio n F art I F u n d am en tals o f t h e V is u a l M echanism The i n t r i n s i c t a l u s o f th e v i s u a l f u n c t i o n endows e v e r y p e rs o n w ith a n a t u r a l i n t e r e s t I n v i s u a l phenomena and h a s s e r v e d t o s t i m u l a t e c o n s id e r a b le s y s t e m a t i c I n v e s t i g a t i o n o f I t s r e l a t e d problem s*

I t is

common know ledge t h a t v i s i o n i s made p o s s i b l e by th e a c t i o n o f l i g h t on a u n i f i e d sy stem c o n s i s t i n g o f t h e eye* t h e o p t i c n e rv e and a s s o c i a t e d gang­ l i a * and t h e v i s u a l c e n t e r i n t h e cerebrum *

The l i g h t h a s i t s e f f e c t upon

th e r e c e p t o r e le m e n ts I n th e r e t i n a o f th e e y e , in d u c in g c h e m ic a l and p h y s i­ c a l changes w h ich l e a d t o t h e i n i t i a t i o n o f n e rv o u s a c t i v i t y i n t h e gang­ l i o n i c n e u ro n e s and f i b e r s o f th e o p t i c n erv e*

I n t h i s r e s p e c t* t h e eye

h o ld s a key p o s i t i o n i n t h e e n t i r e v i s u a l p ro c e s s * and i t i s upon t h e c h e m ic a l an d p h y s i c a l e v e n ts i n t h e r e t i n a * w hich a r e in d u c e d by t h e l i g h t s tim u lu s * t h a t o u r a t t e n t i o n w i l l be fo c u se d * * Of th e s e q u e n c e o f r e a c t i o n s i n i t i a t e d i n th e r e t i n a by th e a c t i o n o f l i g h t , o n ly t h e f i r s t h a s been w e ll e s ta b lis h e d *

H echt (3*4*14*

13*1$* 17* I d ) waft th e f i r s t i n v e s t i g a t o r t o p o s t u l a t e t h a t th e i n i t i a l e v e n t i n th e v i s u a l m echanism c o n s is t e d o f th e r e v e r s i b l e p h o to c h e m ic a l r e a c tio n * L ig h t S v ?+ A ; "D ark"

S - p h o t o s e n s i t i v e p i& aen t P 4* A - p r o d u c ts o f l i # t r e a c t i o n and p r e c u r s o r s o f S

* C o n s id e ra b le in f o r m a tio n h a s a c c u m u la te d c o n c e r n in g th e e l e c t r o p h y s i o l o g i c a l r e l a t i o n s o f th e g a n g lio n ic n eu ro n es* o p t i c n e rv e f i b e r s and r e c e p t o r e le m e n ts* T h is in f o r m a tio n i s n o t p e r t i n e n t t o th e argum ent to be d e v e lo p e d i n t h i s t h e s i s * Hence* t h e r e a d e r i s r e f e r r e d t o H a r t l i n e (3 ) an d e a r l i e r work c i t e d th e r e *

7 T h is schem a h a s sin e® b ee n am ply c o n firm e d by a v a r i e t y o f e v id e n c e w hich h a s l e d o n ly t o m in o r m o d i f i c a t i o n s .

The e v e n ts f o llo w in g th e decom posi­

t i o n o f 3 a r e much m o re o b s c u re and n o t so am enable t o e x p e r im e n ta l ap­ p ro a c h .

K ech t h a s a l s o a tte m p te d a f o r m u la tio n o f t h e s e s u b s e q u e n t e v e n t s ,

b u t th e s u p p o r tin g e v id e n c e i s i n d i r e c t and l e s s c o n v in c in g .

I t is our

p u rp o s e y t h e r e f o r e , t o a tte m p t a b e g in n in g o f an a n a l y s i s o f th e e v e n ts w hich f o llo w t h e d e c o m p o s itio n o f p h o t o s e n s i t i v e s u b s ta n c e s i n t h e r e t i n a . The r e t i n a o f t h e v e r t e b r a t e eye ( 1 ,9 ,1 0 ,3 0 ,3 1 ,3 2 ,3 2 ) a n d , p r e ­ su m ab ly , th e r e t i n a o f any p h o to r e c e p to r c o n ta in s one o r m ore p h o to s e n s i­ t i v e s u b s ta n c e s , w hich have t h e p r o p e r ty o f a b s o rb in g e n e rg y from i n c i d e n t l i g h t and a r e th e r e b y decom posed.

The q u a n t i t y o f e n e rg y w hich i s ab­

s o rb e d v a r i e s w ith th e wave le n g th o f th e l i g h t .

H ence, s p e c t r a l exam ina­

t i o n o f th e l i g h t t r a n s m i t t e d th ro u g h a s o l u t i o n o f s u c h a p h o t o s e n s i t i v e s u b s ta n c e w i l l r e v e a l th e r e g io n s o f th e s p e c tru m from w hich e n e rg y h a s been a b s o rb e d .

By p r o p e r m e asu rem en t, an e n e rg y a b s o r p tio n c u rv e can be r e c o n ­

s t r u c t e d a s shown i n f i g u r e 1 ,

The a r e a u n d e r t h i s cu rv e r e p r e s e n t s th e

amount o f e n e rg y a b s o rb e d by th e p h o t o s e n s i t i v e s u b s ta n c e . The m ost f a m i l i a r p h o to s e n s it iv e p ig m en t p r e s e n t i n th e v e r t e ­ b r a t e r e t i n a i s v i s u a l p u r p le , and th e e f f e c t i v e n e s s o f t h i s s u b s ta n c e i n a b s o rb in g e n e rg y dep en d s upon i t s c o n c e n t r a t i o n .

T h is was d e m o n s tra te d by

th e work o f T a n sle y who p ro v ed t h a t th e p r o g r e s s iv e i n c r e a s e i n s e n s i t i v i t y t o l i g h t o f an e y e i n t h e d a rk , p r e v io u s ly l i g h t a d a p te d , depends upon th e i n c r e a s i n g am ounts o f v i s u a l p u r p le form ed ( 5 0 ) .

I t becomes a p p a r e n t a t

o n ce t h a t th e am ount o f e n e rg y a b s o rb e d from a c o n s ta n t I n t e n s i t y o f i n ­ c i d e n t l i g h t in c r e a s e s a s th e c o n c e n tr a ti o n o f th e a b s o rb in g s u b s ta n c e in c re a se s •

Retina! visibi/ity-percent absorbed

B

too

60 40 20

400

600 W a v e Zen

700

gth -m ju

F ig u r e 1* Tiie s p e c t r a l a b s o r p t io n cu rv e o f v i s u a l p u r p le , ta k e n from //a id (3 1 ) * The l i n e draw n th ro u g h th e c i r c l e s r e p r e s e n t s human ro d v i s i ­ b i l i t y a t th e i n n e r r e t i n a l s u r f a c e .

9 We may s a f e l y assum e t h a t a l l p h o to r e c e p to r s c o n t a i n a p h o to ­ s e n s i t i v e s u b s ta n c e w hich we w i l l c a l l 3 ( 3 3 ) ,

when

f a l l s upon

t h i s s u b s t a n c e , t h e a b s o rb e d e n e rg y c a u s e s i t s d i s i n t e g r a t i o n i n t o two s u b s t a n c e s , p an d A* o r i g i n a l s u b s ta n c e 3 ,

T h ese two breakdow n p r o d u c ts u n i t e t o form t h e l i g h t i s n o t n e c e s s a r y f o r t h i s r e a c t i o n , and

c o n s e q u e n tly i t i a r e f e r r e d t o a s th e d a rk r e a c t i o n a lth o u g h i t may ta k e p la c e b o th i n l i g h t and d a r k .

T hese p o s t u l a t e d r e a c t i o n s g iv e r i s e t o a

r e v e r s i b l e c h e m ic a l sy stem * lig h t s ; * p + " d a rk "

a

The l i g h t r e a c t i o n i s p h o to c h e m ic a l an d o f th e f i r s t o r d e r when l i g h t i s n o t th e lim itin g f a c to r,

E x p e rim e n ta l e v id e n c e c o n firm s t h i s .

A c c o rd in g

t o th e ab o v e f o r m u l a t i o n , t h e d a rk r e a c t i o n i a o f th e se c o n d o r d e r .

T h is

i s a l s o c o n firm e d by e x p e r im e n ta l e v id e n c e ( 1 3 ,1 4 ,1 5 ,1 6 ,1 7 ) , The breakdow n p r o d u c ts P and A e n t e r a n o th e r c h e m ic a l s y ste m i n o r d e r t o p ro d u ce a v i s u a l r e s p o n s e .

I n t h i s r e a c t i o n , P and A c a t a l y z e

th e t r a n s f o r m a t i o n o f a h y p o t h e t i c a l s u b s ta n c e , c a l l e d 1 , i n t o a n o th e r h y p o t h e t i c a l s u b s ta n c e c a l l e d T,

T h is l a t t e r s u b s ta n c e I n i t i a t e s th e a c t i v i t y

* I t i s now w e l l e s t a b l i s h e d t h a t th e p h o to c h e m ic a l r e a c t i o n i n t h e v e r t e ­ b r a t e r e t i n a may be w r i t t e n as , . . . s lig h t v p f 4 f B S ^ " d a r k ” " P + A -+ 0 w here B i s a com ponent r a p i d l y rem oved fro m th e r e t i n a and G i s a com ponent whose q u a n t i t y i s u n lim ite d * F o r v i s u a l p u r p le , t h e s e r e a c t i o n s a r e ; lig h t v is u a l p u r p le * p r o t e i n -t- v ita m in A + v ita m in a d e r i v a t i v e s v i s u a l p u r p le ^ p r o t e i n + v ita m in A + new v ita m in A * d ark " We w i l l , h o w ev er, r e t a i n th e m ore g e n e r a l i s e d n o t a t i o n b e c a u se th e i d e n t i t y o f 3 , p , and A h a v e n o t b een w orked o u t f o r t h e i n s e c t e y e , (5 3 , s e e a l s o 29)

10 l a th e o p t i o n e rv e w hich alw ay s f o llo w s s t i m u l a t i o n o f a n o rm al p h o to ­ r e c e p to r w ith lig h t*

The l a s t p a r t o f t h e H e c h ts ia n th e o r y i s , a s a l ­

r e a d y i n d i c a t e d , th e m o st t h e o r e t i c a l , and t h e e v id e n c e s u p p o r tin g i t i s a t m oat v e r y i n d i r e c t *

The e n t i r e r e a c t i o n s y ste m may be r e p r e s e n te d a s

f o llo w s : lig h t S v— P + A; *d ark »

L

II P + 11

a ||—»T

— > v is u a l s e n s a tio n

11

The f o r m u la tio n g iv e n above c o n ta in s no s u g g e s tio n s a s t o th e p r o b a b le n a t u r e o f t h e s u b s ta n c e T w h ich c a u s e s a c t i v a t i o n o f t h e f i b e r s i n th e o p t i c n erv e*

Xt seem s p e r m is s ib le t o s u g g e s t, h o w ev er, t h a t t h e

c h a r a c t e r i s t i c and c o n s ta n t e l e c t r i c a l p r o p e r t i e s o f th e r e t i n a a r e i n some m anner co n c e rn e d w ith t h e v i s u a l mechanism*

In d e e d , th e f a c t t h a t n e r v e s

a r e e a s i l y e x c i t e d by e l e c t r i c a l s t i m u l i opens th e p o s s i b i l i t y t h a t th e e l e c t r i c a l p o t e n t i a l o f th e r e t i n a may be a m a n i f e s t a t i o n o f t h e a c t i v a t e in g s u b s ta n c e T* $ e l l - o r g a n i z e d p h o to r e c e p to r s s u c h as t h e v e r t e b r a t e e y e , t h e compound ey e o f A rth ro p o d s and t h e ey e o f t h e s q u id , L o ll g o , e x h i b i t v e ry d e f i n i t e e l e c t r i c a l p r o p e r t i e s ( 1 ,5 , 6 ,7 , 1 1 ,1 2 , 2 2 ,2 3 , 2 4 ,2 5 , 2 8 ) .

The e le c ~

t r l c a l p o t e n t i a l s a r e p r e s e n t i n th e r e s t i n g ey e ( i n th e d a r k ) and i n th e a c t i v e ey e ( i n th e l i g h t ) and may be a t t r i b u t e d d i r e c t l y t o t h e s e n s o r y membrane o r r e t i n a *

The o r i e n t a t i o n o f t h i s p o t e n t i a l i s d e te rm in e d by

th e o r i e n t a t i o n o f th e s e n s o r y e le m e n ts ( e . g . r o d s and c o n e s ) i n th e r e t i n a and i s alw ay s s u c h t h a t th e f r e e end o f t h e p h o t o s e n s i t i v e e le m e n ts i s e l e c t r i c a l l y n e g a tiv e to t h e en d c o n n e c te d t o th e f i b e r s o f th e o p t i c n erv e* The p o t e n t i a l d i f f e r e n c e w hich i s th u s o b s e rv e d i s q u i t e c o n s ta n t when th e e y e i s k e p t i n th e dark*

When th e r e t i n a i s i l l u m i n a te d , how ever,

11 t h e m a g n itu d e o f t h e p o t e n t i a l c h a n g e s •

The a l g e b r a i c d i f f e r e n c e betw een

th e p o t e n t i a l o f r e s t an d th e p o t e n t i a l o f t h e il l u m i n a te d r e t i n a l a c a lle d th e r e t i n a l a c tio n p o te n tia l.

The d i r e c t i o n o f t h e r e t i n a l a c t i o n

p o t e n t i a l i s t h e same a s t h a t o f th e r e s t p o t e n t i a l * The r e t i n a l a c t i o n p o t e n t i a l h as s e v e r a l p r o p e r t i e s j

1) A f te r

a b r i e f e x p o su re t o l i g h t , i t may p e r s i s t f o r some tim e { f i g . £ , d iag ram s 5 an d 9 , f ig # 3}*

Z) I n th e e a s e o f a lo n g e x p o s u re t o l i g h t , th e a c t i o n

p o t e n t i a l p e r s i s t s a s lo n g a s th e r e t i n a i s il l u m i n a te d ( f ig # £ , d iag ram 4 )# 3 ) The a c t i o n p o t e n t i a l goes th ro u g h d e f i n i t e f l u c t u a t i o n s i n tim e w h ich a r e q u it© c o n s ta n t u n d e r s i m i l a r c o n d i t i o n s .

When th e m a g n itu d e o f

t h e a c t i o n p o t e n t i a l i s r e c o rd e d in tim e , th e s e f l u c t u a t i o n s r e s u l t I n a c h a r a c t e r i s t i c c o n f i g u r a t i o n w hich i s c a l l e d th e wav© form o f th e re sp o n se * The wave form o f th e r e t i n a l a c t i o n p o t e n t i a l i s so c o n s ta n t f o r t h e same s p e c i e s a n d , to a l e s s e r e x t e n t , f o r a l l a n im a ls , t h a t f o r th e p u rp o se o f r e f e r e n c e c e r t a i n p a r t s o f t h e r e s p o n s e h av e been la b e l e d w ith l e t t e r s ( f i g * 2 , f i g . 3 ) .

a-wave i s alw ays th e i n i t i a l upw ard

d e f l e c t i o n i n th e p o s i t i v e d i r e c t io n *

I n many form s t h i s a-w ave i s a b s e n t

a l t o g e t h e r o r m akes i t s a p p e a ra n c e o n ly u n d e r r e s t r i c t e d c o n d i t i o n s .

When

t h i s i s th e c a s e , t h e i n i t i a l d e f l e c t i o n i s i n th e n e g a tiv e o r downward d i r e c t i o n and i s c a l l e d b-w av e.

The b-wave may o r may n o t be f o llo w e d by

a p ro lo n g e d n e g a t i v i t y , w hich i s c a l l e d th e c-w av e.

The c-w ave i s o f t e n

t e r m i n a t e d , in t h e c a s e o f lo n g e x p o su re t o l i g h t , by a d-wave o r an o f f e f f e c t ( f ig * 8, d iag ram 4}*

The re s p o n s e u s u a l l y ends w ith a s h a r p r e t u r n

to t h e o r i g i n a l b a s e l i n e . The r e c o r d o f t h i s r e t i n a l a c t i o n p o t e n t i a l w ith i t s c o n s ta n t wave form i s c a l l e d an e l e c t r o r e tin o g r a m (ERG) ( 5 ) .

S in c e an ERG i s

MOTH

Figure &* Wave form d iag ram s o f t y p i c a l r e s p o n s e s o b ta in e d fro m i n s e c t ey es* G ra ssh o p p e r r e s p o n s e s a r e i l l u s t r a t e d i n d iag ram s 1 th ro u g h 4 ; 1— o b ta in e d from d a r k - a d a p te d eye w ith a b r i e f h ig h i n t e n s i t y s tim u lu s ; £—r e s p o n s e o f d a r k - a d a p te d ©ye t o a low i n t e n s i t y s tim u lu s ; 3—r e s p o n s e o f t h e l i g h t - a d a p t e d e y e t o a h ig h i n t e n s i t y s ti m u l u s ; 4— r e s p o n s e o f l i g h t a d a p te d eye to a lo n g s tim u lu s o f h ig h i n t e n s i t y * M oth re s p o n s e s a r e i l l u s t r a t e d i n d iag ra m s 5 and 6 ; 5— r e s p o n s e o f d a r k - a d a p te d m oth eye t o a b r i e f s tim u lu s o f h ig h i n t e n s i t y ; 6— re s p o n s e o f l i g h t - a d a p t e d m oth ey e t o a s i m i l a r s tim u lu s * Response* o f th e b e e t l e , C h la e n iu s d i f f i n i s , d u r in g day and n ig h t t o b r i e f , h ig h i n t e n s i t y s t i m u l i a r e i l l u s t r a t e d i n d iag ram s 7 th r o u g h 10; 7— d a r k - a d a p te d d a y -p h a s e r e s p o n s e ; 8— l i g h t - a d a p t e d n i g h t p h ase r e s p o n s e ; 10— l i g h t - a d a p t e d n ig h t- p h a s e re sp o n s e *

13 r e a d i l y r e c o r d e d a f t e r s t i m u l a t i o n o f th e r e t i n a w ith l i g h t , i t h a s been assum ed t h a t t h i s e l e c t r i c a l wave i s somehow a s s o c i a t e d w ith v i s i o n . T oday, a c o n s id e r a b l e body o f e v id e n c e p o i n t s t o th e c o n c lu s io n t h a t th e a c t i o n p o t e n t i a l i s a n e x p r e s s io n o f th e r e t i n a l p h y s ic o -c h e m ic a l mech­ an ism r e s p o n s i b l e f o r v i s u a l phenom ena.

The e v id e n c e l i e s i n th e p e r f e c t

ag reem en t i n s t u d i e s o f v a r io u s v i s u a l f u n c tio n s by t h e s u b j e c t i v e method* ( r e f l e x r e s p o n s e o r s p e e c h ) and by th e e l e c t r i c a l m ethod*

(Compare th e

p a p e rs o f H ech t an d s t u d e n t s w ith H a r t l i n e , G r a n it, e t a l , Jo h n , e t a l , C h a ffe e , e t a l . ) F a rt I I Q u a n t i t a t i v e a s p e c t s o f th e V is u a l M echanism I t h a s a l r e a d y b e e n m e n tio n e d t h a t th e q u a n t i t y o f e n e rg y w hich i s rem oved from t h e l i g h t d ep en d s i n p a r t* upon th e c o n c e n t r a t i o n o f th e p h o to s e n s itiv e s u b s ta n c e .

P resum ably t h e s u b s ta n c e S i n th e r e t i n a can be

m a in ta in e d a t a c o n s ta n t maximum c o n c e n tr a ti o n by k e e p in g t h e ey e i n a s t a t e o f m axim al d a rk a d a p t a t i o n .

When th e q u a n t i t y o f s i s c o n s ta n t, th e am ount

o f e n e rg y a b s o rb e d d epends up o n t h e i n t e n s i t y o f th e i n c i d e n t l i g h t and upon t h e d u r a t i o n o f t h e i l l u m i n a t i o n . F o r any g iv e n c o n s ta n t am ount o f e n e rg y a b s o rb e d by a p h o to c h e m ic a l s y s te m , t h e I n t e n s i t y o f t h e l i g h t s o u rc e and th e tim e o f i l l u m i n a t i o n b e a r a r e c i p r o c a l r e l a t i o n t o ea ch o t h e r , so t h a t th e i n t e n s i t y - t i m e p ro d u c t i s * Zn t h e p a s t , two m ethods h a v e been u se d i n t h e s tu d y o f r e t i n a l p h y s i­ o lo g y , s u b j e c t i v e m easurem ents and o b j e c t i v e m e a su re m e n ts• S u b je c tiv e phenom ena o f v i s i o n in v o lv e t h e p r o p e r t i e s o f s e n s o r y e le m e n ts o f th e r e t i n a , th e n e rv o u s o r g a n i s a t i o n o f t h e r e t i n a and th e ’’i n t e g r a t i n g a c t i o n o f th e h i g h e r c e n t e r s . ” I n c e r t a i n c r i t i c a l e x p e rim e n ts i t i s p o s s ib le t o o b ta in in f o r m a tio n by s u b j e c t i v e m easurem ent w hich i s a p p l i c a b l e d i r e c t l y t o th e v i s u a l m echanism o f t h e r e t i n a . The o b j e c t i v e m e asu rem en ts, on t h e o t h e r h a n d , a r e p erfo rm e d d i r e c t l y on th e e l e c t r i c a l r e s p o n s e o f th e r e t i n a ( 5 ) . H ence, u n c e r t a i n t y o f l o c a t i o n o f v i s u a l phenomena i s n o t so g r e a t a h a z a rd i n th e i n t e r p r e t a t i o n o f d a t a o b ta in e d i n t h i s m an n er.

U p r o p o r t i o n a l t o th e q u a n t i t y o f e n e rg y ab so rb ed *

T h is r e l a t i o n may sim p ly

be e r itte n « E

=

fe lt

w here E I s t h e e n e rg y a b s o rb e d o r t h e p h o to c h e m ic a l e f f e c t , k i s a c o n s ta n t o f p r o p o r t i o n a l i t y an d I t I s t h e I n t e n s i t y - t i m e p ro d u c t*

T h is s im p le s t a t e ­

m ent i s th e w e l l known r e c i p r o c i t y law o f B unsen and Roseoe* When t h e tim e o f i l l u m i n a t i o n i s h e ld c o n s ta n t t h e p h o to c h e m ic a l e f f e c t w i l l be a f u n c t i o n o f th e i n t e n s i t y *

H ence, ch an g es in th e s t i m u l a t ­

i n g I n t e n s i t y w i l l p ro d u c e ch an g es i n th e p h o to c h e m ic a l e f f e c t * b etw een E an d X h a s b een d e te rm in e d by two d i f f e r e n t m e th o d s .

The r e l a t i o n U sin g t h e

tim e from b e g in n in g o f i l l u m i n a t i o n u n t i l r e t r a c t i o n o f t h e s ip h o n o f t h e c la m , Mya a r e n a r i a , H e eh t (1 8 ) o b ta in e d t h e r e l a t i o n t h a t E

=

In X

H ow ever, when t h e p h o to c h e m ic a l e f f e c t i s m easu red a s t h e amount o f P an d A fo rm ed , t h e r e l a t i o n s h i p p ro v e s t o be m ore com plex ( s e e f i g u r e s & an d 6)* Two r e l a t i o n s h i p s b etw een t h e c o n c e n tr a tio n o f F and A and th e i n t e n s i t y o f th e s t i m u l a t i n g l i g h t h av e b een p ro v id e d by H eeht*

One r e l a t i o n s h i p was

o b ta in e d from t h e b le a c h in g o f v i s u a l p u r p le i n v i t r o and a n o th e r from t h e l i g h t a d a p te d p h o to r e c e p to r o f t h e c lam , Mya a r e n a r i a , u s in g th e s ip h o n r e t r a c t i o n r e f l e x aa a c r i t e r i o n o f re sp o n s e * I n a d d i t i o n t o p ro d u c in g ch an g es i n th e p h o to c h e m ic a l e f f e c t , d i f f e r e n t i n t e n s i t i e s o f s t i m u l a t i n g l i g h t w i l l a l s o p ro d u ce ch an g es in t h e m a g n itu d e o f t h e ERG*

H ence, a s th e m ax im ally d a r k - a d a p te d eye i s s t i m u l a t e d

by l i g h t o f p r o g r e s s i v e l y i n c r e a s i n g I n t e n s i t y , th e m ag n itu d e o f th e ERG w i l l a l s o i n c r e a s e I n a v e ry r e g u l a r m anner*

B ecause o f t h i s p r e c i s e r e l a t i o n s h i p

b etw ee n th e s t i m u l a t i n g I n t e n s i t y an d th e e le c tr o m o tiv e f o r c e o f th e r e t i n a ,

15 i t wad d e c id e d t o i n v e s t i g a t e t h e M T * i n t e n s i t y r e l a t i o n s h i p f o r a number o f I n s e c ts *

The r e s u l t s o b ta in e d w i l l be com pared w ith th e above c i t e d

d a t a p ro v id e d by H e e h t, and an a tte m p t w i l l be made t o c l a r i f y th e r e l a t i o n b etw een t h e breakdow n p r o d u c ts , p and A, o f th e p h o to c h e m ic a l r e a c t i o n , and th e e l e c t r i c a l r e s p o n s e o f t h e r e t i n a * H a rt I I I I n t r o d u c t i o n to e x p e r im e n ta l M a te r i a l I n t e n s I t y - M F s t u d i e s w ere p erfo rm ed o n b e e t l e s , g r a s s h o p p e r s , and s e v e r a l s p e c i e s o f m oths*

The g ra s s h o p p e rs w ere o f two t y p e s , n am ely ,

norm al m t a o t a n im a ls and a n im a ls w ith t h e c e r e b r a l and o p t i c g a n g lia removed*

P r e v io u s w ork (£8) h a s shown t h a t th e o p t i c g a n g lio n c o n t r ib u t e s

c o n s id e r a b ly t o th e e l e c t r i c a l re s p o n s e o f th e i n t a c t compound eye*

H ence,

i t s re m o v a l was deemed a d v i s a b le i n o r d e r t o s tu d y th e i n t e n s l t y - M F r e l a t i o n * s h ip s o f th e r e t i n a a lo n e *

The a n im a ls w ith o u t c e r e b r a l an d o p t i c g a n g lia

w i l l be r e f e r r e d t o aa d e - g a n g lio n u te d g ra ss h o p p e rs * The in te n sity -E M F s t u d i e s on th e b e e t l e s w ere made i n c o n n e c tio n w ith a v i s u a l d i u r n a l rh y th m (3 4 )*

V is u a l d i u r n a l rhythm s p r e s e n t i n th e

ey es o f t h e g round b e e t l e , C h la e n lu s d i f f i n i s , and th e w a te r b e e t l e , H ydrous t r i a n g u l a r i s , w ere f i r s t d e s c r ib e d by Jah n and C r c a c i t e l l i i n 1940 (£ 4 )* L a te r a s i m i l a r v i s u a l d i u r n a l rhythm was d e s c r ib e d f o r th e p re d a c io u s d iv i n g b e e t l e , D y tls c u s f a s c l v e n t r l s { 2 b ) ,

One m a n i f e s t a t i o n o f t h i s v i s u a l d i u r n a l

rhythm I s a p e r i o d ic v a r i a t i o n i n th e form o f th e KKG ( f ig * £» d iag ram s 7 and 9 , f ig * 3 )*

D u rin g th e d a y , (a p p ro x im a te ly from 7 A.M* to 3 p.M*) a

b r i e f f l a s h (17 m sec*} o f l i g h t e l i c i t s from th e d a r k - a d a p te d compound eye o f C h la e n lu s and H ydrous a r e s p o n s e w hich c o n s i s t s o f a n i n i t i a l b-w&ve

16 fo llo w e d by a p ro lo n g e d n e g a t i v e w ave, t h e c-w ave ( f i g . S , d iag ram 9 , f ig . 3 ).

F o r t h e b e e t l e D y t l s c u s , th e wave form o f th e day and n ig h t

ty p e r e s p o n s e s d i f f e r *

D u rin g th e d a y , th e r e s p o n s e o f th e d a r k -a d a p te d

compound e y e o f P y t i a e u s , a g a in t o a b r i e f f l a s h o f l i g h t * c o n s i s t s o f a n i n i t i a l p o s i t i v e d e f l e c t i o n * an a~wave, fo llo w e d by a f a s t r e t u r n to t h e b a s e l i n e ( f i g * 3* p y tlsc u ® d ay p h a s e , h ig h i n t e n s i t y ) .

D u rin g t h e

n i g h t , th e r e s p o n s e , u n d e r i d e n t i c a l c o n d i t i o n s , c o n s i s t s o f an a-wav@ s p ik e whose m a g n itu d e i s s u b j e c t t o c o n s id e r a b le v a r i a t i o n , fo llo w e d by a com plex p ro lo n g e d n e g a tiv e wave w hich i s d iv id e d i n t o two p a r t s , and Qg ( f i g . 3 , D y tls c u s n i g h t p h a s e , h ig h i n t e n s i t y ) . The v i s u a l rh y th m i n D y tls c u s h a s been exam ined i n c o n s id e r a b le d e t a i l (@ 5,£$,£7}»

The r e s u l t s o f t h e s e o b s e r v a tio n s i n d i c a t e t h a t t h e

c h an g e s i n t h e v i s u a l sy ste m w ere s u f f i c i e n t l y p ro fo u n d

00

t h a t one m ig h t

c o n s id e r t h e ey e d u r in g th e day and d u r in g th e n ig h t as two d i s t i n c t p h o to r e c e p to r s w ith t o t a l l y d i f f e r e n t v i s u a l p r o p e r tie s *

H ence, f o r co n ­

v e n ie n c e , t h e e y e d u r in g th e day i s r e f e r r e d t o a s th e day-phas© eye and d u rin g t h e n i g h t us th e n ig h t- p h a s e eye* iimong t h e s e v e r a l d i f f e r e n c e s i n v i s u a l p r o p e r t i e s e s t a b l i s h e d f o r t h e d a y -a n d n i g h t - p h a s e ey es o f t h e b e e t l e D y tls c u s , th e r e i s a p r o ­ nounced ch an g e i n th r e s h o l d s e n s i t i v i t y .

D uring th e n i g h t , th e m ax im ally

d a r k -a d a p te d e y e w i l l j u s t re sp o n d t o an i n t e n s i t y o f l i g h t w hich i s 1000 tim e s lo w e r th a n t h e i n t e n s i t y w hich w i l l j u s t p ro d u c e a r e s p o n s e I n th e m a x im a lly d a r k -a d a p te d e y e o f t h e d a y -p h a se b e e tle *

I n t h i s c o n n e c tio n ,

i t was d e c id e d t o i n v e s t i g a t e t h e s e n s i t i v i t y r e l a t i o n s h i p o f t h e d a y -a n d n ig h t- p h a s e e y e s o v e r an i n t e n s i t y ra n g e b e g in n in g a t t h e t h r e s h o l d i n t e n s i t y and i n c r e a s i n g t o t h e maximum i n t e n s i t y a v a i l a b l e .

1? HYDROUS HIGH I N T E N S IT Y

LOW NTENSITY DAY PHASE

ir

NIGHT PHASE

■

y " D YTISC US

DAY PHASE N IG H T PHASE

F ig u re 3 , Ware fo ira d iag ram s o f th e e l e c t r i c a l r e s p o n s e s o b ta in e d from e y e s o f t h e w a te r b e e t l e s , Hydrous t r i a n g u l a r i s and D y tls c u s f a s c i v e n t r i s , i n a d a r k -a d a p te d s t a t e w ith b r i e f s t i m u l i o f h ig h an d low i n t e n s i t y * R e fe r t o te x t f o r f u r th e r d e ta il#

18 M a t e r i a l and M ethod The a n im a ls u s e d w e re o b ta in e d i n th e f o llo w in g m anner;

G ra ss ­

h o p p e rs w ere ta k e n fro m a l a b o r a t o r y c o lo n y ; m oths w ere h a tc h e d from c o c o o n s, some o f w hich w ere c o l l e c t e d and o t h e r s o f w hich w ere o b ta in e d from a co m m ercial s u p p ly h o u s e ; b e e t l e s w ere c o l l e c t e d from l o c a l ponds an d k e p t i n a q u a r i a i n t h e l a b o r a t o r y « I n o r d e r t o o b t a i n th e e l e c t r i c a l re s p o n s e from th e e y e , th e a n im a ls w ere p r e p a re d a s fo llo w s ( 8 ) ;

th e body an d h e a d o f t h e i n s e c t

w ere s e c u r e l y f a s t e n e d t o a p a r a f f i n block*

B lack l i q u i d p a r a f f i n was

a p p l i e d t o th e s i d e o f t h e h ead t o b u i ld a r i n g aro u n d th e edge o f th e co rn e a*

The to p o f th e r i n g mm rem oved,

p ro d u c in g a h o rs e s h o e -s h a p e d

p r o j e c t i o n fro m t h e s i d e o f t h e h ead w ith th e c o rn e a a t i t s c e n te r* T hese cham bers w ere f i t t e d w ith g l a s s end p l a t e s , one o f w hich was r e n d e re d opaque t o l i g h t , and f i l l e d w ith s a l t s o lu tio n *

The a n im a ls w ere p la c e d

on a t r a y and g l a s s s ip h o n s f i l l e d w ith s a l t s o l u t i o n made e l e c t r i c a l con­ t a c t b etw een th e cham bers an d l a r g e r r e s e r v o i r s o f s a l t s o l u t i o n .

The

r e s e r v o i r s c o n ta in e d n o n - p o la r iz a b le e l e c t r o d e s , one o f w hich was c o n n e c te d t o t h e g r id o f t h e a m p l i f i e r .

The t r a y was p la c e d in an e l e c t r o d e cham ber

c o n t a i n i n g g l a s s windows and one ey e was s t i m u l a t e d w ith known i n t e n s i t i e s o f l i g h t f o r s p e c i f i e d p e r io d s o f tim e*

The e l e c t r i c a l re s p o n s e s w ere

a m p lif ie d by a v a r i a b l e - t i m e * c o n s t a n t , h ig h - g a in a m p l i f i e r and w ere re c o rd e d on s e n s i t i s e d p a p e r by means o f a c a th o d e ray. o s c illo g r a p h *

The m a g n itu d e

o f t h e r e s p o n s e was t r a n s l a t e d i n t o m ic r o v o lts and th e s e d a ta w ere p l o t t e d a s shown i n t h e g ra p h s w hich follow *

R e s u l t s and D is c u s s io n F a rt X In te n s ity -S M F

R e l a t i o n s i n t h e P ark -A d ap ted Eye

X* R e s u lts a* N oim al g r a s s h o p p e r, M elan o p lu s d i f f e r e n t i a l i a

( f ig * 4 , t a b l e l )

I n a s t a t e o f m axim al d a rk a d a p ta tio n , t h e s e a n im a ls w ere s tim u ­ l a t e d w ith i n t e n s i t i e s r a n g in g from 0«01 f o o t c a n d le t o 1 0 ,0 0 0 f o o t c a n d le s #

D u rin g t h e e x p e r im e n ts , a re c o v e ry i n t e r v a l o f 10 t o 30 m in u te s

was a llo w e d b etw een e a c h t e s t f l a s h —10 m in u te s f o r v e ry low i n t e n s i t i e s , i n c r e a s e d p r o g r e s s i v e l y t o 30 m in u te s a t maximum i n t e n s i t y *

T h is was

n e c e s s a r y i n o r d e r t o m a in ta in a m ax im ally d a r k - a d a p te d s t a t e * The r e s p o n s e o f t h e g r a s s h o p p e r to a b r i e f s tim u lu s c o n s i s t s o f a s im p le n e g a t i v e wave ( f ig # S, d iag ram 1 )*

H ence, a m easurem ent o f th e

d e p th o f t h e b -w av e, i# e * t h e d i s t a n c e from th e b a s e l i n e t o t h e bottom o f th e w ave, a f f o r d s a s im p le m ethod o f d e te r m in in g t h e m ag n itu d e o f t h e r e ­ s p o n s e i n m ic r o v o lts #

I n f ig * 4 , t h e s e v a lu e s o f t h e r e s p o n s e m ag n itu d e

a r e p l o t t e d a g a i n s t th e lo g a r ith m o f th e c o r re s p o n d in g I n te n s i t y #

The

r e s u l t i s a sm ooth 3 -s h a p e d cu rv e* b* D e -g a n g lio n a te d g r a s s h o p p e r, M« d i f f e r e n t i a l i s T h ese a n im a ls w ere o p e r a te d upon i n th e f o llo w in g m anner:

th e

e x o s k e le to n o f t h e f r o n t o f th e h ead was r m o v e d and th e o p t i c and c e r e b r a l g a n g l i a w ere s im p ly l i f t e d o u t#

W ith a m o d e ra te am ount o f c a r e t h i s o p e r a ­

t i o n c a n be e x e c u te d w ith n e g l i g i b l e i n j u r y t o t h e eye#

The s i t e o f o p e r a ­

t i o n was s e a l e d w ith a p a r a f f i n c a p , and t h e a n im a l was m ounted as p r e v io u s ly d e s c rib e d #

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F ig u r e 4* I n d i v i d u a l i n t e n s i t y-SMF c o n to u rs f o r th e d a r k -a d a p te d ey e o f th e g ra s s h o p p e r (n o rm a l a n d d e - g a n g lio n a te d .) an d th e m o th s , Sam ia c y n th la and Sam ia c e c r o p i a . The d a t a w ere o b ta in e d by t r a n s l a t i n g th e d e p th o f t h e r e s p o n s e a s m e a su re d from t h e b a s e l i n e ( f ig * 2, d iag ram s 1 and 5 ) I n to m ic r o v o lts an d p l o t t i n g t h e s e v a lu e s a s p e r c e n t o f t h e r e s p e c t i v e maxima* The a b c i s s a r e p r e s e n t s th e lo g a r ith m t o t h e b a se 10 o f th e i n t e n s i t y i n f o o t c a n d le s * The c o n to u r s a r e s e p a r a t e d f o r c l a r i t y and th e l a s t p o i n t o f ea c h c u rv e c o rre s p o n d s to t h e a b c i s s a Log I - 4 , R e fe r t o t e x t f o r f u r t h e r d e ta ils •

21

T a b le I S e n s i t i v i t y B a ta In te n s ity

1 0 ,0 0 0 f . c . 1 ,0 0 0 100 10 1 0*1 0 .0 1

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100 95 85*7 7 0 .8 3 5 .1 9 .5 5 3 .0 3

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100 97*4 8 1 .7 5 4 7 .6 2 8 .9 1 4 .2 4 .4

The e l e c t r i c a l r e s p o n s e o f t h e d e - g a n g lio n a te d ey e to b r i e f l i g h t s t i m u l i i s s i m i l a r t o t h a t o f a n o rm a l a n im a l.

The in te n s ity -m C F

r e l a t i o n s h i p i s s i m i l a r t o t h a t f o r th e n o rm a l g r a s s h o p p e r ( f i g . 4 ) . c* N orm al m o th s, Sarnia c e e r o p ia and Sami a e y n th la ( f i g . 4 , t a b l e I ) Two s p e c i e s o f m o th s , Sarnia o e o r o p la and Sarnia e y n th l a , w ere t r e a t e d I n a m anner s i m i l a r t o t h a t u s e d w ith th e g ra s s h o p p e rs *

The

d a r k - a d a p te d e y e o f t h e s e a n im a ls g iv e s a n e l e c t r i c a l re s p o n s e to a b r i e f l i g h t s tim u lu s w h ich c o n s i s t s o f a p ro lo n g e d n e g a tiv e wave ( fig * 2) com­ p o se d o f an i n i t i a l f a s t b -w ave, f o llo w e d by a much s lo w e r c-w av e*

The

m a g n itu d e o f b o th b -a n d o-w aves in c r e a s e s i n a v e ry r e g u l a r m anner as t h e s t i m u l a t i n g i n t e n s i t y in c r e a s e s *

The g ra p h f o r c e e r o p ia r e p r e s e n t s th e

i n t e n s i t y - M F r e l a t i o n f o r t h e b-w ave; th e g rap h f o r e y n th la r e p r e s e n t s t h e in te u 3 ity -E M F r e l a t i o n f o r th e c-wave*

w ith th e e x c e p tio n o f t h e

su d d en f l a t t e n i n g o f t h e c e e r o p ia c u rv e a t th e h ig h i n t e n s i t y e n d , b o th f o llo w e s s e n t i a l l y t h e same c o u rse * 2 . D is c u s s io n The f o u r in te n s ity -S M F c u rv e s f o r th e d a r k -a d a p te d i n s e c t ey e i n d i c a t e a s i m i l a r i t y i n t h e p r o c e s s e s r e s p o n s i b le f o r th e p r o d u c tio n o f th e r e t i n a l a c tio n p o te n tia l*

The in c r e a s e d t h r e s h o l d and d e c r e a s e d

l e v e l o f re s p o n s e o f th e d e - g a n g lio n a te d g r a s s h o p p e r eye may perh ap s be a t t r i b u t e d t o a g r e a t e r s p r e a d o f th e p o t e n t i a l due t o in c r e a s e d volume o f t h e c o n d u c to r betw een t h e e y e s c a u sed by rem o v al o f th e n erv o u s elem en ts* I n o r d e r t o c o n s t r u c t a l o g i c a l argum ent as t o t h e n a tu r e o f t h e s e p r o c e s s e s , we m u st b e g in w ith known e v e n ts i n th e r e t i n a w hich a r e i n i t i a t e d by t h e l i g h t s tim u lu s *

S in c e we a r e d e a lin g w ith th e m a x im a lly d a r k - a d a p te d

23 •y e* i t i s c e r t a i n t h a t t h e c o n c e n t r a t i o n o f p h o t o s e n s i t i v e m a t e r i a l i n th e r e t i n a o f a n y o n e a n im a l i s a lw a y s a t a maximum* and p resu m ab ly t h i s maximum i s c o n s t a n t .

The s t i m u l a t i n g l i g h t a c t s upon t h i s p h o to ­

s e n s i t i v e p ig m en t c a u s in g I t s d e g r a d a tio n i n to two s u b s ta n c e s . s ------- > >

+

a

The e x t e n t o f t h e degradation o f 3* o r th e amount o f p and h e d e n o te d a s t h e p h o to c h e m ic a l e f f e c t .

a

formed* mey

The m ag n itu d e o f th e p h o to ­

c h e m ic a l e f f e c t depends u p o n t h e i n t e n s i t y and tim e o f s t i m u l a t i o n . S in c e t h e tim e o f i l l u m i n a t i o n (17 m s e c .) i s c o n s ta n t i n a l l e x p erim en ts* t h e s t i m u l a t i n g i n t e n s i t y is t h e o n ly in d e p e n d e n t v a r i a b l e a f f e c t i n g th e m a g n itu d e o f th e p h o to c h e m ic a l e f f e c t . A lth o u g h t h e p h o to c h e m ic a l breakdow n o f t h e s u b s ta n c e 3 i s u s u a l l y c o n c e iv e d t o be a r e v e r s i b l e r e a c tio n * we may n e g l e c t th e M a rk ” r e a c tio n * * +

A -------- > 3

f o r t h e f o llo w in g r e a s o n s $ 1 . ) The c o n c e n t r a t i o n o f 3 i s m axim al a t

th e

b e g in n in g o f t h e s tim u lu s * h e n c e th e r e a c t i o n c a u s in g a n i n c r e a s e i n 3 i s in s ig n ific a n t*

£#} The e l e c t r i c a l r e s p o n s e b e g in s w ith in 10 m sec, a f t e r

b e g in n in g o f s t i m u l u s .

H ence, we may assum e t h e nearly form ed p and A

a c t i v e i n p ro d u c in g t h e re s p o n s e i s u n d im in ish e d by t h e r e l a t i v e l y slo w d a r k r e a c t i o n * whose s p e e d I s c o n t r o l l e d by th e c o n c e n t r a t i o n o f P and A. Thus* th e p h o to c h e m ic a l p ro c e ss* in t h i s s p e c i a l c a s e o f maximum d a rk a d a p t a t i o n and a b r i e f s ti m u l u s , may be c o n s id e r e d a s a r e a c t i o n whose sp e e d o f p r o d u c tio n o f P an d A i s c o n t r o l l e d by th e i n t e n s i t y o f th e s tim u lu s *

A t h e o r e t i c a l l y s im p le tr e a tm e n t o f t h i s problem w ould be to

m e a su re th e am ount o f P + A form ed i n th e r e t i n a a f t e r s t i m u l a t i o n , b u t

24 t h e t e c h n i c a l d i f f i c u l t i e s in v o lv e d i n th e p ro c e d u re a r e a t p r e s e n t i n s u r ­ m o u n ta b le*

H ow every a n e x p e r im e n ta l s i t u a t i o n a n alo g o u s to th e d a r k -

a d a p te d ey e was s e t up by H eeht ( 1 9 ,2 0 ) , in w hich h e d e te rm in e d t h e v e lo ­ c i t y o f th e b le a c h in g r e a c t i o n o f v i s u a l p u r p le i n v itr o *

The v i s u a l

p u r p le e x t r a c t s em ployed by H eeh t d id n o t show any r e - s y n t h e s i s o f p h o to ­ s e n s i t i v e m a t e r i a l a f t e r b le a c h in g .

H ence, in h i s t r e a tm e n t, th e r e v e r s e

r e a c t i o n o f t h e p h o to c h e m ic a l breakdow n o f 3 , P + k — > 3 , d id n o t o c c u r , t and th e b le a c h in g p r o c e s s was t r e a t e d a s a f i r s t o r d e r r e a c t i o n whose v e l o c i t y i s a f u n c t i o n o f t h e c o n c e n tr a tio n o f v i s u a l p u r p le .

T h e re fo re ,

t h e K i n e t i c s o f t h e p h o to c h e m ic a l s y ste m i n t h i s p a r t i c u l a r c a s e a r e s i m i l a r t o t h e K i n e t i c s o f th e p h o to c h e m ic a l s y s te m i n th e d a r k -a d a p te d e y e s ti m u l a t e d o n ly b r i e f l y w ith l ig $ i t, f o r i n b o th in s ta n c e s th e r e v e r s e o r " d a rk ” r e a c t i o n i s n o n - e x i s t e n t . H eeh t m easu red th e b le a c h in g v e l o c i t y o f d i f f e r e n t sam p les o f v i s u a l p u r p le i l l u m i n a te d w ith d i f f e r e n t i n t e n s i t i e s o f l i g h t an d fo u n d t h a t t h e v e l o c i t y c o n s t a n t , k , i n c r e a s e d i n a l i n e a r f a s h io n w ith t h e illu m in a tin g in te n s ity * S in c e t h e s e e x p e rim e n ts o f H eeht a r e p e r t i n e n t t o th e p r e s e n t d i s c u s s i o n o n ly i f th e y can s u p p ly u s w ith in f o r m a tio n a p p l i c a b l e t o th e In te n sity -U & F s t u d i e s o n th e d a r k - a d a p te d e y e , i t seemed a d v is a b le t o d e te rm in e i n w hat f a s h i o n th e breakdow n p ro d u c ts o f v i s u a l p u r p le w ere r e l a te d to th e illu m in a tin g in te n s ity *

£ m

lo g ^

a-,>x

The f a m i l i a r e q u a tio n , k * v e l o c i t y c o n s ta n t 2 .3 = f a c t o r f o r c o n v e rs io n o f n a t u r a l i n t o common lo g a r ith m a • I n i t i a l c o n c e n tr a tio n o f S x * c o n c e n t r a t i o n o f p o r A a t tim e t»

may be m o d ifie d to p ro d u c e th e f o llo w in g r e l a t i o n s ;

fro m w hich I t i s e v id e n t t h a t a p l o t o f x a g a i n s t lo g I , t « c o n s ta n t , m a s t p ro d u c e a s ig m o id curve* V a lu e s o f (x ) f o r any g iv e n tim e and i n t e n s i t y o f i l l u m i n a t i o n w ere c a l c u l a t e d f o r a s e r i e s o f i n t e n s i t i e s r a n g in g from

1

to

100

fo o t

c a n d le s a n d f o r 0 * 5 , 3 , 4 , and 5 m in u te s i l l u n i n a t i o n a t each i n te n s i ty * T hese d a t a a r e r e c o r d e d i n t a b l e IX* The c o n to u r s o f f i g u r e & w ere o b ta in e d by p l o t t i n g th e p e r c e n t c o n c e n t r a t i o n o f ( x ) a g a i n s t t h e lo g a r ith m o f th e i n t e n s i t y , p r o d u c i n g th e t r u e s i ©noi d cu rv e s* We may sum m arize th e s e o b s e r v a tio n s i n th e s ta te m e n t t h a t th e i n t e n s i t y - c o n c e n t r a t i o n o f (x ) r e l a t i o n i s such t h a t , f o r s m a ll v a lu e s o f It,

(x ) i n c r e a s e s s lo w ly ; f o r i n te r m e d ia te v a lu e s o f th e I t p r o d u c t, { x )

i n c r e a s e s r a p i d l y ; and f o r h ig h value** o f I t , (x ) in c r e a s e s a g a in more s lo w ly , th u s p ro d u c in g t h e S -sh a p e d curve*

T h e r e f o r e , had a l a r g e r ra n g e

o f i n t e n s i t i e s been em ployed, th e t y p i c a l s -a h a p e d c u rv e m ust be o b ta in e d f o r any one tim e o f i l l u m in a tio n * R e tu r n in g t o t h e i n t e n s ity -JM F r e l a t i o n s o f t h e d a r k -a d a p te d i n s e c t - e y e , i t i s a p p a r e n t a t o n ce t h a t th e c o n to u r s o f M F and c o n c e n tr a ­ t i o n o f (x ) w ith r e s p e c t t o s t i m u l a t i n g i n t e n s i t y r u n p a r a l l e l c o u rs e s * H ence, we may c o n c lu d e t h a t th e m ag n itu d e o f th e e l e c t r i c a l r e s p o n s e o f t h e d a r k -a d a p te d i n s e c t e y e v a r i e s a p p ro x im a te ly a s th e c o n c e n tr a tio n o f p a n d /o r A*

I f P a n d /o r

a

i s / a r e a c a t a l y s t f a c i l i t a t i n g a n o th e r m ono-

m o le c u la r r e a c t i o n I n v o lv in g an e le c tr o m o tiv e a g e n t, th e n t h e s u b s ta n c e L, p o s t u l a t e d by H e e h t, e x i s t s and th e r e t i n a l a c t i o n p o t e n t i a l may be th e a c t i v a t i n g a g e n t , T»

9C H

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F ig u r e 5 . I n t e n s i t y - p e r o e n t c o n c e n tr a t io n o f (x ) c o n to u r s c a l c u l a t e d fro m d a t a o f H echt* The c u rv e s r e v e a l th e r e l a t i o n betw een t h e r a t e o f f o r m a tio n o f P and A and t h e I n t e n s i t y and tim e o f i l l u m i n a t i o n . A ll c u r v e s , e x c e p t th e & m in u te c o n to u r , have b een a r b i t r a r i l y s h i f t e d t o th e r i g h t * The l a s t p o i n t o f ea c h c u rv e c o rre s p o n d s t o t h e a b c is s a lo g 1 • 2* R e fe r t o t e x t f o r m ore d e t a i l .

27

T a b le I I * I n t . ( m .c .)

In t. ( f .c .)

12

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3 2 .5

4 .8 6 9 .2 5

100

225 440 670 @85 1000

2 0 .8

4 0 .3 6 2 .0 8 1 .9 92*5

1 .0 8 1 .7 2 2 .0

2 .3 5 2 .6 4 2 .3 3 2 .9 6 3 .0

Log I ( f . c . ) 0*041 0 .6 8 7 0 .9 6 6 1 .5 1 8 1 .6 0 0 1 .7 9 2 1 .9 1 3 1 .9 6 6

3 M in . 1 1 .9 2 7 .6 39 , 1 6 8 .4 9 0 .0 9 6 .8 4 100 100

4 M in.

0 .0 1 1

0 .0 2 7 0 .0 4 3 0 .1 0 0 .2 0

0 .3 0 0 .4 0 0 .4 5

9 .6 2 2 .8

3 2 .7 0 0 .2

8 4 .2 9 3 .7 9 7 .4 9 9 8 .4 2

3 M in. 7 .4 1 7 .6 2 5 .7 4 9 .9 7 4 .9 8 7 ,4 1 9 3 .7 9 5 .5 4

A b b r e v ia tio n s : m .o . = m e te r c a n d le f . c . - f o o t c a n d le Log 1 * lo g a r ith m o f I n t e n s i t y ( b a s e 10)

*

T.

P e r P e a t C o n c e n tr a tio n o f (x )

Log I n t . ( f . c . )

0 .0 4 1 0 .6 8 7 0 .9 6 6 1 .3 1 8 1 .6 0 6 1 .7 9 2 1 .9 1 3 1 .9 6 6

M g I ( m .e .)

D ata r e c a l c u l a t e d from th e w ork o f H e c h t. ( 1 9 ,8 0 ) .

0*2 3 .1 4 .9 1 0 .9 20.6 2 9 .2 5 3 6 .9 4 0 .5

28 P a rt II I n te n s lty ~ B £ F R e la tio n s In t h e L ig h t-A d a p te d Eye X, R e s u lts a . Norm al g r a s s h o p p e r , M* d i f f e r e n t i a l i s

( f ig *

6

, ta b le I I I )

T h e se a n im a ls w ere p r e p a re d a s th o s e a lr e a d y d e s c r ib e d .

A f te r

b e in g p la c e d I n t h e e l e c t r o d e cham ber, th e y w ere p e r m itte d to re a c h a s t a t e o f m axim al d a r k a d a p t a t i o n .

Then th e y w ere s tim u la te d once e v e ry

se c o n d w ith a h a l f - s e c o n d s tim u lu s o f l i g h t o f t h e lo w e s t i n t e n s i t y u s e d . The r e p e t i t i v e s t i m u l a t i o n was c o n tin u e d u n t i l th e c o n s ta n c y o f th e e l e c t r i c a l r e s p o n s e i n d i c a t e d t h a t t h e ey e had re a c h e d a s t a t e o f e q u i l i ­ brium w ith t h a t I n t e n s i t y ; a t t h i s tim e a p h o to g ra p h ic r e c o r d o f th e re s p o n s e was t a k e n .

The I n t e n s i t y o f s t i m u l a t i o n was th e n in c r e a s e d and

t h e p r o c e s s r e p e a t e d f o r eac h h i g h e r l e v e l o f s t i m u l a t i o n .

The m ag n itu d es

o f th e r e s p o n s e s w ere d e te rm in e d i n m i c r o v o l t s , and th e s e v a lu e s w ere con­ v e r t e d t o p e r c e n t o f maximum and p l o t t e d a g a i n s t t h e c o r re s p o n d in g lo g ­ a r ith m ic v a lu e s o f t h e s t i m u l a t i n g i n t e n s i t y ( f i g . ©, c u rv e f o r norm al g ra ssh o p p e r). b . D e -g a n g lio n a te d g r a s s h o p p e r , M* d i f f e r e n t ! a l l s

(fig .

6

, t a b l e XXX)

T h e se a n im a ls w ere f i r s t o p e r a te d u p o n , a s d e s c r ib e d p r e v io u s ly , to rem ove t h e o p t i c and c e r e b r a l g a n g lia l y i n g b etw een th e e y e s .

A f te r

t h i s o p e r a t i o n , th e y w ere m ounted i n a m anner s i m i l a r t o th e o t h e r s and p e r m itte d t o r e a c h a s t a t e o f m axim al d a rk a d a p t a t i o n .

They w ere th e n

s ti m u l a t e d r e p e t i t i v e l y w ith h a lf - s e c o n d s t i m u l i c o v e r in g th e e n t i r e i n t e n s i t y ra n g e .

The m a g n itu d e o f t h e r e s p o n s e was p l o t t e d a g a i n s t th e lo g a r ith m o f

t h e c o r re s p o n d in g i n t e n s i t y ( f i g . ta b le

111

).

6

, c u rv e f o r d e - g a n g llo c a te d g r a s s h o p p e r,

100

r 100

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80

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F ig u r e 6 . I n d i v i d u a l ( I H- A I ) « W c o n to u rs f o r t h e l i g h t - a d a p t e d noxmal an d d e - g a n g lio n a te d g r a s s h o p p e r; and I n t e n s i t y - s t e a d y s t a t e an d - ( x + A i ) c o n to u rs f o r an y p h o t o r e c e p t o r f o b ta in e d from d a t a o f H echt# The s te a d y s t a t e c u rv e d e s c r i b e s t h e e q u ilib r iu m c o n c e n t r a tio n o f P o r A a t any i n t e n s i t y o f a d a p ta tio n # The ( x + A x ) c u rv e d e s c r ib e s th e new P o r A form ed when t h e a d a p tin g i n t e n s i t y i s i n c r e a s e d by an amount A I# The c u rv e s a r e s e p a r a t e d f o r c l a r i t y and th e f i n a l p o in ts o f th e l a s t t h r e e c o n to u rs c o r re s p o n d t o t h e a b c i s s a lo g 1*4# R e fe r t o t e x t f o r f u r t h e r d e ta il#

30

T a b le I I I ta g I

-2*3 -1*3 - 0*8 0*7 1 .7 2 .7 8*7

*

♦per Cent Cone, o f % 1.4 8 .8 6 10

28*5 62 92 99

ta g (l + A I) -2 —1 0 1 2

3 4

( x -f- A x )

2*0 5 .3 6 1 4 .0 3 6 .8 7 3 .4 9 5 .3 9 9 .4

p a t e o b ta in e d from work o f H ech t ( 2 1 ) .

Normal Grasshop. 4*7 9 .1 3 3 2 .3 5 4 .4 8 8 .2

9 7 .2 100

Ueguftfi* Grasshop •55 2 .5 1 2 .8

3 6 .4 6 2 .5 8 8 .5 100

51 2# D is c u s s io n One o f t h e c o m p lic a tin g f a c t o r s i n t h i s e x p e rim e n t a r i s e s from th e r e p e t i t i v e s t i m u l a t i o n w ith h a lf - s e c o n d e x p o s u re s o f l i g h t .

The

a n im a ls a r e i n t h e d a r k f o r h a l f o f any s p e c i f i e d i n t e r v a l o f tim e and a r e s t i m u l a t e d by l i g h t f o r t h e r e m a in in g h a l f .

T h is s i t u a t i o n c o r r e s ­

ponds t o s t i m u l a t i o n w ith f l i c k e r i n g l i g h t , a n d , t h e r e f o r e , t h e i n t e n s i t y o f l i g h t to w h ich th e eye o f t h e a n im a l a d a p ts i t s e l f i s h a l f th e a c t u a l s t i m u l a t i n g i n t e n s i t y u sed *

T h is a d a p tin g I n t e n s i t y we may r e f e r t o a s

th e s t e a d y - s t a t e i n t e n s i t y .

The e l e c t r i c a l r e s p o n s e o f th e ey e t o th e

s t e a d y - s t a t e I n t e n s i t y i s n o t re c o rd e d b ec a u se i t form s th e b a se l i n e fream w h ich t h e a c t u a l re s p o n s e s a r e m e a su red . S in c e th e e y e i s a d a p te d t o h a l f o f th e a c t u a l stim u la tin g i n t e n s i t y , t h e n , d u r in g t h e h a l f se c o n d i n w hich i t i s I llu m in a te d , t h e r e i s a n a v e ra g e i n c r e a s e i n i n t e n s i t y above th e l e v e l o f a d a p t a tio n a ls o e q u a l to h a l f o f t h e t o t a l s t i m u l a t i n g i n t e n s i t y #

T h is in c r e a s e i n i n ­

t e n s i t y d u r in g e a c h h a l f se c o n d o f s t i m u l a t i o n may be c a l l e d

AX ( d e l t a I ) ,

and t h e e l e c t r i c a l r e s p o n s e w hich i s m easu red i s r e l a t e d to t h i s i n c r e a s e above t h e a v e ra g e l e v e l o f s t i m u l a t i n g i n t e n s i t y #

H ence, th e c u rv e s f o r

n o rm al and d e - g a n g lio n s te d g ra s s h o p p e rs a r e p r o p e r ly d e s ig n a te d a s ( I + A I ) IMF r e l a t i o n s ( f i g #

6

)#

I t l a now im p e r a tiv e t o answ er th e q u e s tio n a s t o how t h e s e IMF c u rv e s a r e r e l a t e d t o t h e breakdow n p ro d u c ts o f th e p h o to s e n s i tiv e s u b ­ s ta n c e ,

To a p p ro a c h i t i n s u i t a b l e f a s h i o n , w© t u r n a g a in t o t h e work o f

H echt (2 1 ),

T h is i n v e s t i g a t o r d e v is e d a m ethod, baaed upon s u b j e c t i v e

d a t a , f o r d e te r m in in g th e c o n c e n t r a t io n o f P and A a f t e r t h e p h o to c h e m ic a l s y ste m h ad e s t a b l i s h e d e q u ilib r iu m a t any i n t e n s i t y o f s t i m u l a t i n g l i g h t #

32 T h is m eth o d was d e r iv e d by H ech t from t h e k i n e t i c s o f th e two r e a c t i o n s w h ich a r e n o rm a lly p r e s e n t i n a p h o to r e c e p to r s tim u la te d f o r a c o n s id e r — a b l e l e n g t h o f tim e , nam ely L ig h t B

P + A "d ark *

The v e l o c i t y o f t h e l i g h t r e a c t i o n depends upon th e c o n c e n tr a ­ t i o n o f 3 and t h e i n t e n s i t y o f t h e s ti m u l a ti n g l i ^ i t #

L et u s c a l l th e

m axim al c o n c e n t r a t i o n o f 3 , a t t a i n e d i n a s t a t e o f mmcimel d a rk a d a p ta ­ t i o n , ( a ) , an d c a l l th e c o n c e n tr a t io n o f e i t h e r P o r A r e s u l t i n g from th e a c t i o n o f l i g h t , (x )*

Then th e v e l o c i t y o f th e l i g h t r e a c t i o n may be

s ta te d as Ti ■ The v e l o c i t y o f t h e d a rk r e a c t i o n i s governed s o l e l y by th e c o n c e n t r a t i o n o f t h e p r o d u c ts p and

a*

T h e re f o re , th e v e l o c i t y o f t h i s

r e a c t i o n may be f o rm a lly s t a t e d as »2 * *2x2 A t e q u ilib r iu m th e s e v e l o c i t i e s a r e e q u a l. I k i t a - x ) * kgx 2

H ence, we may w r i t e

• K

5

Kg Com bining th e c o n s ta n ts an d t h e v a r i a b l e s , we o b ta in th e f i n a l r e l a t i o n

from w hich t h e v a lu e s o f (x ) and ( a -x ) may be o b ta in e d f o r any s ti m u l a t i n g in te n s ity *

fro m th e d a t a p r e s e n te d by H echt o n ly t h a t f o r th e c o n c e n tr a ­

t i o n o f (x ) was c h o se n ; t h e s e d a ta s r e r e - p l o t t e d in f ig u r e s te a d y s t a t e *

6

, cu rv e f o r

I n t h i s c a s e th e p e r c e n t c o n c e n tr a tio n o f (x ) i s a f u n c tio n

o f t h e lo g a r ith m o f th e i n t e n s i t y to w hich th e eye has become adapted*

33 The v a lu e o f ( x ) f o r any i n t e n s i t y r e p r e s e n t s th e e q u ilib r iu m c o n c e n tr a ­ tio n o f p o r A in th e r e t i n a . From th e s te a d y s t a t e r e l a t i o n we may o b ta in th e in fo r m a tio n n e c e s s a r y to r e l a t e t h e c o n c e n t r a t i o n o f p and A to th e ( I -h c u rv e s o f f i g u r e

6

*

A I ) - SMF

The minimum r e p e t i t i v e s t i m u l a t i n g i n t e n s i t y , i . e .

th e i n t e n s i t y which i s a c t u a l l y f a l l i n g upon th e eye e v e ry h a l f s e c o n d , is 0 .0 1 f o o t c a n d l e , a p p r o x im a te ly .

From p re v io u s d is c u s s io n we know t h a t ,

i n t h i s i n s t a n c e , t h e I n t e n s i t y , I , w ith w hich th e p h o to c h e m ic a l r e a c t i o n e s t a b l i s h e s e q u i l i b r i u m i s j u s t h a l f th e s t i m u l a t i n g i n t e n s i t y , o r 0 .0 0 5 f o o t c a n d le .

(T h is c o rre s p o n d s t o th e lo w e s t p o in t on t h e s t e a d y - s t a t e

c u rv e o f f i g . © w here lo g I i s e q u a l t o - 2 * 3 .)

T h e r e f o r e , th e in c r e a s e i n

l e v e l o f s t i m u l a t i o n d u r in g t h e h a l f seco n d i l l u m i n a ti o n i s a l s o e q u a l to 0*005 f o o t c a n d le ( A l t ) and t h e t o t a l i n t e n s i t y , (X -+• A I , ) f a l l i n g upon t h e eye I s e q u a l t o 0*01 f o o t c a n d le .

The amount o f (x ) w hich i s

foxmed by t h i s i n c r e a s e i n s t i m u l a t i n g i n t e n s i t y c a n be o b ta in e d from th e s t e a d y - s t a t e c u rv e by s u b t r a c t i n g th e o r d i n a t e o f lo g X - - 2 .3 ( 0 .0 0 5 f . c . ) from t h e o r d i n a t e o f l o g . 1 - 2 amount o f ( x ) , o r A x ,

( 0 .0 1 f . c . ) *

The d i f f e r e n c e w i l l be th e

w hich i s foxmed by th e in c r e a s e o f i n t e n s i t y , A I .

S in c e we a r e i n t e r e s t e d i n o b ta i n i n g th e q u a n tit y (x n e c e s s a r y t o r e a d th e o r d i n a t e s o f lo g X * - 2 , - 1 , s ta te c u rv e.

+

A x),

(I +

AX)*

T hese v a lu e s o f (x

p lo tte d a g a in s t th e i n t e n s i t y

0

-t ,

1

A x ) , i t i s o n ly e t c . on th e s te a d y -

f o r p u rp o se s o f c l a r i t y , a r e T h is p ro d u ces t h e (x 4-

A x)

c u rv e o f f i g u r e w hich i s i d e n t i c a l to th e s t e a d y - s t a t e c u r v e . C om parison o f t h e c u r v e s r e v e a l s t h a t IMF and (x + s i m i l a r l y r e l a t e d t o e q u a l v a lu e s o f (X -h

AX).

A x ) a re

When v a lu e s o f (x 4-

A x)

34 an d a m f o r c o r re s p o n d in g i n t e n s i t i e s a r e p l o t t e d a g a in s t each o t h e r , a s e r i e s o f p o i n t s r e s u l t s w h ich c a n b e d e s c r ib e d by a l i n e o n ly s u b t l y co n cav e upward*

T h is a p p r o x im a te ly l i n e a r r e l a t i o n i s to be e x p e c te d

fro m t h e a p p e a ra n c e o f t h e ( x 4-

A x)-(X

4- A l ) and M F ~ (I 4-

a I)

c o n to u rs • T h is a n a l y s i s o f d a ta o b ta in e d from th e l i g h t a d a p te d e y e t h e r e ­ f o r e le n d s s u p p o r t t o th e c o n c lu s io n made in th e p re v io u s s e c t i o n , nam ely, t h a t t h e m a g n itu d e o f t h e e l e c t r i c a l r e s p o n s e o b ta in e d from th e i n s e c t e y e s upon s t i m u l a t i o n w ith l i g h t d epends upon th e c o n c e n tr a tio n o f th e breakdow n p r o d u c ts o f t h e p h o to c h e m ic a l r e a c t i o n . P a rt I I I I n t e n s l t y - M F R e la tio n s f o r B e e tle s p o s s e s s in g a V is u a l D iu rn a l Rhythm. 1* R e s u lts a . D y tis c u s f a s c i v e n t r i s T h ese b e e t l e s w ere ta k e n from th e a q u a r i a , w here th e y were ex­ p o se d t o n o rm a l c o n d itio n s o f day and n ig h t , and were mounted i n an e l e c t r o d e cham ber w here th e y w ere i n c o n s ta n t d a r k n e s s . rem oved t h e s tim u lu s r e s p o n s i b le f o r th e rh y th m .

T h is e f f e c t i v e l y

N e v e r th e le s s , th e v i s u a l

d i u r n a l rh y th m p e r s i s t e d f o r s e v e r a l days in a l l t h e b e e t l e s t e s t e d .

The

an H m U w ere p la c e d i n th e e l e c t r o d e chamber d u r in g th e h e ig h t o f e i t h e r th e day o r t h e n ig h t phase*

A f t e r r e a c h in g a s t a t e o f m axim al d a rk a d a p ta ­

t i o n , th e y w ere s t i m u l a t e d w ith b r i e f f la s h e s (17 m s e c .) o f l i g h t o f v a ry ­ in g i n t e n s i t y , an d th e m ag n itu d e o f th e r e s p o n s e was r e c o r d e d .

Two com­

p l e t e d e te r m in a tio n s o v e r t h e e n t i r e i n t e n s i t y ra n g e were made on each b e e t l e , one d u r in g th e day phase and on© d u r in g th e n ig h t p h a se .

* iv e

b e e t l e s w ere exam ined in t h i s m anner, th e r e s u l t s a v erag ed and p l o t t e d on

35 c o o r d i n a t e p a p e r t o p ro d u c e t h e c u rv e s o f f i g u r e

7

.

The r e s u l t s a r e d iv id e d in to d a y -p h a se and n ig h t- p h a s e d a t a , & s i n g l e c u r v e d e s c r i b e s t h e e l e c t r i c a l re s p o n s e o f th e d a r k -a d a p te d d a y -p h a s e ey e o f t h e b e e t l e b eca u se th e re s p o n s e i s s im p le , c o n s i s t i n g o n ly o f a n a-w av e © pike ( f i g . 3 , B y tis c u s day p h a s e , h ig h and low i n t e n s i t y ) . T h is d a y -p h a s e c o n to u r i n d i c a t e s t h a t th e a-w ave I n c r e a s e s s t e a d i l y w ith i n c r e a s i n g I n t e n s i t y o f s t i m u l a t i o n and re se m b le s c l o s e ly t h e lo w er p o r tio n o f t h e p e r c e n t c o n c e n t r a t i o n o f ( x iia & e n s tty c u rv e s o f f i g u r e

5

.

The e l e c t r i c a l re s p o n s e o f t h e a ig h t-p h a s© ay© la d e s c r ib e d by two c u r v e s b ec a u se o f t h e com plex wave f o r a o f th e ERG ( f ig * 5 , B y tis c u s n i $ i t p h a s e , h ig h i n t e n s i t y ) .

The n ig h t-p h ae© a-w ave c o n to u r ( f i g . 7)

i n d i c a t e s t h a t th e a -w a v e , i n c r e a s i n g s t e a d i l y from a v e ry low i n t e n s i t y ( 0 . 0 1 f o o t c a n d l e ) , r e a c h e s a maximum a t 50 f o o t c a n d le s and d e c lin e s w ith i n c r e a s i n g i n t e n s i t y .

The n ig h t-p h a s© c-w aves c o n to u r i s a l s o

co m p lex , f o r two d i s t i n c t com ponents a r e e v id e n t.

The lo w er lim b o f t h i s

c u rv e i n d i c a t e s t h a t t h e Cg-wave makes i t s a p p e a ra n c e w ith lo w er i n t e n s i t i e s , r e a c h e s a maximum s l i g a t l y b e h in d th e a-w ave maximum, an d i s th e n s u p e rc e d e d by th e e^ -w av e, which l e v e l s o f f a t h ig h i n t e n s i t y , b . H ydrous t r i a n g u l a r i s (H y d ro p h ilu s ) T h e se b e e t l e s a r e t r e a t e d i n th e same m anner a s t h e b e e t l e s o f t h e genus B y tis c u s *

I n t h i s s p e c ie s th e v i s u a l d i u r n a l rhythm a ls o p e r ­

s i s t s f o r s e v e ra l days.

J n t e n s i t y - M F m easurem ents a r e made on t h e

a n im a ls d u r in g t h e h e i g h t o f th e day an d n ig h t p h a s e .

The r e s u l t s o b ta in e d

from s e v e r a l b e e t l e s a r e a v e ra g e d t o g e t h e r and p l o t t e d on c o o r d in a te p a p e r t o p ro d u c e t h e c u rv e s o f f i g u r e

8

.

10090-

80-

LJ 70Ld

60-

Ld 50-

40-

30-

20-

10-

-2 LOG

I

Figure 7# I n t e n a i t y - 2MF c o n to u rs f o r s e v e r a l com ponents o f th e e l e c t r i c a l r e s p o n s e fro m th e d a r k —a d s p te d ey e o f th e b e e tle * l)y t i s c u s f a s c i v e n t r i s . The n i g h t p h a se a-w ave and n ig h t p h ase Cjj_ and Cg-waves a r e com ponents o f t h e same r e s p o n s e . A ll t h e m ag n itu d e s a r e c o n v e rte d t o p e r ©ent o f t h e i r r e s p e c t i v e maxima# R e fe r to t e x t f o r f u r t h e r d e t a i l #

3?

T a b le I ? M agnitude - P e r C ent In te n s ity

Log JI

%

N ig h t P h ase A-wave

0 .0 1

0 .0 5

f . c.

-8

0 .5 1 6 1

5 .1 6 10

5 1 .6 75 100

516 1000

5160 10000

*0*4 0 0 .6 1 1 .6

1 .8 7 6 2 a .6 3 3 .6 4

Ci-wave

4 .0 9

—1 .4

0 .1

Op-wnve

Day P h ase

« * * * « » « * « •*

0 .9 5 1 1 .7 3 2 .4 3 7 .6 5 6 .4 7 8 .5 9 8 .1 9 3 .6 8 9 .4 71 63 5 4 .9 5 1 .1

A-wave

7 .5 1 6 .4 8 3 6 .2 5 4 .5

»W*—> w W Q «*««*«»«»

0 .6 1 5

m o — -wi*w»

3 .3 6

m w o

im «■»

mmomrn

1 0 .7 ■■ m» ttmmm+m o m m m m

3 0 .7 6 5 ,8

n o m — «— w»

81 9 8 .2 100

5 5 .8 100

38 1100

1000 9 00 800 700 6 0 0 -^ 5 0 0 -> 400 300

200 100

-2 LO G

F ig u r e

8

I

.

I n te n s ity - I M F c o n to u r s f o r s e v e r a l com ponents o f t h e e l e c t r i c a l re s p o n s e from t h e d a r k -a d a p te d ey e o f th e b e e t l e , H ydrous t r i a n g u l a r i s * $ h e n i g h t p h ase b-arid c-w ave c u rv e s r e p r e s e n t com ponents o f th e same re sp o n s e * A l l m a g n itu d e s a r e p l o t t e d d i r e c t l y i n m i c r o v o l t s . R e f e r to te x t fo r fu rth e r d e ta ils .

39

T a b le V

Magnitude - M icrovolts I n te n s ity

N ig h t Pitas e

IflMB JE

C-wave

B-wave 0 * 00127fife* - 2 .9 0 8 0*005 -2 * 3 0*01

0*05

-1

.8

0*1

0*3 1 .0

3 .0

-0 * 3 0 :- 0 .7

e 10 20

38 63 80 9 3 .3

Bay Phase

«* «»«»***« i

** « * > * * * * *

10*0

1 .0

198*5

230

1*7

■ N tM k ffM * .—

« * « ■ * * •* » * *

100

2

269

4 0 1 .3

500

2*7 3 3 .7 4

3000 10000

22

4»a* «*«»**

781 — —

. 301

M M « * •* * »

1 0 .7 5 16 .7 5

120

— « ••■ » * * * •

286

« n < * * « •« * « »

4»«* **«*«»

50*0

1000

B-w&ve

■«■

1092*5

43 57 115 174 242 249

40 l&a r e s u l t s e r e d iv id e d I n to day—p h a s© and Eight»pU& 9 e d a te * && i n D y b iso u s , t h e e l e c t r i c a l re s p o n s e o f th e d a rk —a d a p te d day**phase H ydrous ey e i s d e s c r ib e d by a e i n g le c u rv e ( f ig *

8

, D.p* b-w ave) b ecau se

t h e wave form o f th e ERG i s s i a p le ( fig * 3 , Hydrous d ay phase* h ig h in te n s ity ) •

T h is c u rv e re s e m b le s th e Dyt is c u s day--phase a-w ave r e l a t i o n

an d i s s i m i l a r t o t h e lo w e r p o r ti o n o f th e c u rv e s o f f i g u r e

5

.

The e l e c t r i c a l r e s p o n s e o f th e n ig h t-p h a s e ey e o f Hydrous i s d e s c r ib e d by two c o n to u r s b ec au se o f th e c o m p le x ity o f th e wave form o f th e ERG ( f i g . 3 , H ydrous n ig h t p h a s e f h ig h i n t e n s i t y ) *

The r e l a t i o n ­

s h i p s b etw een t h e n ig h t- p h a s e b - and c-w ave c o n to u rs a r e i n t e r e s t i n g . F irs t*

i t may be o b s e rv e d t h a t th e m ag n itu d e o f th e c-w ave in c r e a s e s

f a r m ore r a p i d l y w ith h ig h e r i n t e n s i t y o f s ti m u l a t i o n th a n does t h e m a g n itu d e o f th e b-wuve ( f i g *

8

).

S econdly* th e lov* i n t e n s i t y end o f

t h e b-w ave c o n to u r c o n ta in s a d i s t i n c t b re a k a t lo g I * *1*

The p o r ti o n

o f t h e c u rv e below t h i s b re a k i s d i s t i n c t l y concave upw ard and i s con­ n e c te d * w ith b ro k e n l i n e s , to th e c-w ave c u r v e . 2

. P is c u s s io n The i n t e a s i t y - f f l F r e l a t i o n s o b ta in e d from th e two s p e c ie s o f

b e e t l e s a r e , w ith s e v e r a l e x c e p tio n s , s i m i l a r to th e d a rk -a d a p te d eye con­ to u r s o f f i g u r e 4#

The

y t i s c u s d a y -p h a se r e l a t i o n ( f i g s . ? ) d e p a r ts

fro m the t y p i c a l sig m o id s h a p e , b u t does no v io le n c e to the argument presented, fo r it e shape is e s s e n tia lly s im ila r to the lower p o rtio n o f the contours o f fig u re 6 .

Hence, w ith the exception o f the Bjrtieous n ig h t-

phase a-wave contour, the re s u lts obtained from the beetles confirm the conclusion th a t th e magnitude o f the e le o tric a l response is some

41 a p p r o x im a te ly l i n e a r f u n c t i o n o f th e c o n c e n t r a t i o n o f breakdown p r o d u c ts , P an d A,

T he D y tis c u s n i g h t - p h a s e a-w ave r e l a t i o n ( f i g , 7 ) p r e s e n ts no

s e rio u s o b s ta c le ,

As a l r e a d y m e n tio n e d , th e m a j o r i t y o f th e p o t e n t i a l s

( e . g , g r a s s h o p p e r s , m o th s , an d H ydrous) m easu red w ere o f a n e g a tiv e s ig n and o f q u i t e s i m i l a r wave fo rm th ro u g h o u t t h e i n t e n s i t y r a n g e .

The

B y tis c u s n i g h t p h a s e r e s p o n s e , how ever, ch an g es q u i t e r a d i c a l l y i n wave form fro m low t o h ig h i n t e n s i t i e s o f s t i m u l a t i o n , and th e p o l a r i t y o f th e r e s p o n s e te n d s to become r e v e r s e d .

T h e r e f o r e , we may te m p o r a r ily d is m is s

t h i s anom aly by a t t r i b u t i n g i t to th e c o m p le x ity o f t h e wave form o f t h e re sp o n se . The D y tis c u s d a y -p h a se a-w ave c o n to u r ( f i g , 7) i s o f i n t e r e s t a ls o b ecau se a

l i n e a r r e l a t i o n s h i p may be o b ta in e d when t h e m ag n itu d e o f

t h e r e s p o n s e i s p l o t t e d a g a i n s t th e s q u a r e r o o t o f t h e i n t e n s i t y .

T h is

i s p r e c i s e l y th e r e l a t i o n o b ta in e d by C h a ffe e , Bovie and Hampson (7 ) from a n a l y s i s o f i n t e n s i t y - M F d a t a from th e f r o g r e t i n a .

I n a l a t e r p u b lic a ­

t i o n ( 8 ) C h a ffe e an d Hampson I n d i c a t e d , how ever, t h a t th e s ta te m e n t M B * k l 'i h o ld s t r u e f o r o n ly a l i m i t e d p o r ti o n o f t h e d a t a , and e x te n s io n o f th e I n t e n s i t y a x i s i n t h e d i r e c t i o n o f e i t h e r h ig h e r o r lo w er i n t e n s i t y p ro d u c e s d a t a w hich i s d i s t i n c t l y n o t l i n e a r u n d e r t h e s e c o n d i t i o n s . The in te n a ity -B /IF c o n to u rs o f f i g u r e s 7 and

8

a ls o in d ic a te

d i s t i n c t d iff e r e n c e © i n s e n s i t i v i t y t o l i g h t o f t h e d a y - and n lg h t- p h a a e ey es*

Z t h a s b een shown ( 2 § ) t h a t t h e th r e s h o ld i n t e n s i t y o f t h e d a r k -

a d a p te d n i g h t - p h a s e e y e i s a s much a s

1000

tim e s lo w er th a n th e th r e s h o ld

I n t e n s i t y f o r t h e d a r k - a d a p te d d a y -p h a se ©ye.

The d a t a p r e s e n te d h e re show

t h a t t h e s e d i f f e r e n c e s i n s e n s i t i v i t y to l i g h t a t th r e s h o ld p e r s i s t

42 throughout almost the e n tire in te n s ity range (compare magnitudes o f the night-phase and day-phase re la tio n e , o f fig s , 7 and 8 ) ,

Hence, we may

say th a t during the night phase o f the d iu rn a l rhythm the w ater beetles are much more s e n s itiv e to lig h t than during th e day phase,

43 C o g cy u g io g

I t h a s a l r e a d y b e e n m entioned, t h a t , when c o rre s p o n d in g v a lu e s o f (x - t A x ) an d WtW (n o rm a l g r a s s h o p p e r , f i g ,

6

) a re p lo tte d a g a in s t

e a c h o t h e r a a e r i e s o f p o i n t s r e s u l t s w hich i s d e s c r ib e d by a l i n e o n ly s l i g h t l y co n cav e upward*

t h e n t h e l o g a r i t h m o f th e s e v a lu e s a r e p l o t t e d

i n s t e a d , th e m a j o r i t y o f t h e point© f a l l on a s t r a i g h t l i n e .

On th e b a s is

o f th e g ra p h o f t h i s r e l a t i o n s h i p we may s t a t e t h a t X « BIF3**3, When t h e (x

-h A x } an d d e - g a n g lio n a te d g ra s s h o p p e r d a ta a r e s i m i l a r l y

t r e a t e d , t h e lo g * lo g p l o t produce© p o in ts w hich a r e s c a t t e r e d ©bout a s tra ig h t lin e .

The s l o p e o f t h i s l i n e i s 1 ,0 ,

I n t h i s c a s e we may make th e

s ta te m e n t x * mat* C o n s id e r a tio n o f th e s e r e l a t i o n s and th o s e m ore a p p ro x im a te r e l a t i o n s o b ta in e d from th e d a rk -a d a p te d eye ( f i g , 4 and f i g , 5) le a d s to t h e I n e v i t a b l e c o n c lu s io n t h a t th e m agnitude o f th e r e t i n a l a c t i o n p o t e n t i a l i s a l i n e a r f u n c t io n o f th e c o n c e n tr a tio n o f p a n d /o r A, S in c e © l e c t m a o t i v e ly a c t i v e a g e n ts , s u c h a s o x id a n ts an d r e due t a n t s o r d i f f u s i b l e io n s , alw ays b e a r a lo g a r ith m ic r e l a t i o n betw een t h e i r c o n c e n tr a tio n and th e W d u c ts , P

p ro d u c e d , we know t h a t th e breakdow n p r o ­

and A, o f t h e p h o to c h e m ic a l r e a c t i o n c a n n o t be th e agent© r e ­

s p o n s ib le f o r th e r e t i n a l a c tio n p o te n tia l.

I t i s q u i t e p o s s i b l e , how ever,

t h a t th e l i n e a r r e l a t i o n o f P a n d /o r A to W F may be th e r a t h e r t y p i c a l r e l a t i o n o f enzyme c o n c e n tr a tio n t o v e l o c i t y o f r e a c t i o n , w here p a n d /o r A i s th e enzym© and th e HMF i s a m easu re o f r e a c t i o n r a t e .

I f th is is so ,

44 then th e in te rm e d ia te re a c tio n postulated hy H echt, t

|j

P +

A

1|

>t

may he the mechanism producing the r e t in a l a c tio n p o te n tia l and th is p o te n tia l may w e ll he the a c tiv a tin g agent T*

45 Summary 1* I t h a s b e e n shown t h a t th e m a g n itu d e o f t h e e l e c t r i c a l re s p o n s e i n c r e a s e s i n a n o r d e r l y m aim er w ith i n c r e a s i n g s t i m u l a t i n g i n t e n s i t y .

When t h e

m a g n itu d e o f t h e r e s p o n s e ia p l o t t e d a g a i n s t th e lo g o f i n t e n s i t y , a s i g ­ m oid c u r v e i a o b t a i n e d . 2 . By p ro p e r t r e a t m e n t o f d a t a ta k e n from t h e work o f H e c h t, i t h a s been shown t h a t t h e c o n c e n t r a t i o n o f breakdow n p r o d u c ts in c r e a s e s i n a n o r d e r l y m anner w ith I n c r e a s i n g s t i m u l a t i n g i n t e n s i t y .

The c u rv e s o b ta in e d when th e

c o n c e n t r a t i o n o f p o r A i s p l o t t e d a s a f u n c t io n o f tix© lo g a r ith m o f th e i n t e n s i t y a r e s ig m o id i n n a t u r e . 3 . The s i m i l a r r e l a t i o n s h i p o f th e IMF o f th e r e t i n a l a c t i o n p o t e n t i a l and c o n c e n t r a t i o n o f th e p h o to c h e m ic a l r e a c t i o n p r o d u c ts , P a n d /o r A, t o th e s t i m u l a t i n g i n t e n s i t y i n d i c a t e t h a t a l i n e a r r e l a t i o n e x i s t s betw een th e c o n c e n t r a t i o n o f P o r A and th e m a g n itu d e o f th e e l e c t r i c a l r e s p o n s e . 4* P o r A c a n n o t be th e e le e tr o m o tiv e ly a c t i v e a g e n ts p ro d u c in g th e r e t i n a l a c tio n p o te n tia l. 5 . P a n d / o r A may p o s s ib ly c a t a ly z e a r e a c t i o n p ro d u c in g th e r e t i n a l a c t io n p o te n tia l. 6 . The B S F -p ro d u cin g m echanism may p o s s i b ly be th e in te r m e d ia te r e a c t i o n

p o s t u l a t e d by H e c h t. 7 . T he a g e n t T, w hich i n i t i a t e s a c t i v i t y i n th e o p t i c g a n g l i a and o p t i c n e r v e , may be t h e r e t i n a l a c t i o n p o t e n t i a l .

L ite ra tu re I* Reviews G r a n i t , R* 1938 p r o c e s s e s o f a d a p ta t io n i n t h e v e r t e b r a t e r e t i n a i n t h e 1 1 g i t o f r e c e n t p h o to c h e m ic a l and e l e c t r o p h y s i o l o g i c a l r e s e a r c h * Documents O p th a lm o lo g ic s, v o l . 1 . H a r t l i n e , H . K#

1948

S e n se o rg an s*

Ann. Rev* o f P h y s i o l . , v o l* 4 , p .

H e c h t, S* 193? R o d s, cones and th e c h e m ic a l b a s i s o f v is io n * R e v ., v o l . 1 7 , p . 239. 1938

The n a t u r e o f th e v i s u a l p ro c e ss *

P h y s io l*

The H arvey L e c tu re s *

K o h lra u s c h , a* 1931 Bis c k t r is c h e K rsch ein u n g en am A uge. Handbuch d e r N orm alen und P a th a lo g is c h e n P h y s io lo g le , v o l . 1 2 / 2 , p , 1393* 11* S p e c if ic P a p e rs C h a f f e e , B o v ie , and Hampson 1923 The e l e o t r i c a l r e s p o n s e o f th e r e t i n a u n d e r s t i m u l a t i o n by l i g h t 4 Jo u r* O p tic a l Soc* o f m e r * , v o l . p* ! • C h a ffe e an d Hampson 1924 E f f e c t s o f v a r y in g th e w a v e -le n g th o f t h e s tim u la tin g l i g h t upon t h e e l e o t r i c a l r e s p o n s e o f th e r e t i n a * Jo u r* O p t i c a l Soc* o f A m er., vol* 9 , p* 1* C r e e c i t e l l i , F* and T . L . J a h n 1939 The e l e c t r i c a l re s p o n s e o f th e d a r k - a d a p te d g ra s s h o p p e r eye to v a r io u s i n t e n s i t i e s o f illu m in a ­ t i o n and to d i f f e r e n t q u a l i t i e s o f l i g h t* Jo u r* C e ll* and Comp* P h y s i o l * , v o l . 1 3 , p* 1* G r a n it, R*, T* H olm berg, and M. Zewi 1938 A c tio n o f v i s u a l p u r p le on ro d c e l l s * Jo u r* o f P h y s i o l . , vol* 94, p* 430* G r a n i t , R«, A* M u n ste rh je lm , and M* Zewi 1939 V is u a l p u r p le and r e t i n a l s e n s itiv ity * Jo u r* o f P h y s io l* , v o l , 9 6 , p* 3 1 , H a r t l i n e , K, A, 1923 The e l e c t r i c a l re s p o n s e to i l l u m i n a t i o n o f th e eye i n i n t a c t a n im a ls , in c lu d in g th e human s u b j e c t ; and I n d e c e r e b r a te p r e p a r a t i o n s * Amer, J o u r , o f P h y s i o l . , v o l* 7 3 , p . 600. ...

#

-

— —« 1 9 2 7 q u a n t i t a t i v e and d e s c r i p t i v e s tu d y o f th e e l e c t r i c r e s p o n s e to i l l u m i n a t i o n o f th e A rth ro p o d eye* Amer* J o u r, o f P h y s io l* , v o l . 8 3 , p* 466* 1989 The d a rk -a d a p t a t io n o f th e e y e o f L im u lu s, as m a n if e s te d by i t s e l e c t r i c r e s p o n s e t o illu m in a tio n * J o u r o f Gen* P h y s io l* , v o l* 1 3 , p* 379.

47 14* H e c h t, 3* 1919 S e n s o ry e q u ilib r iu m and d a rk a d a p t a t i o n i n Mya a r e n a r i a . lo u r * Gen. P h y s i o l . , v o l . 1 , p . 5 4 5 . 15*

1919 The n a t u r e o f th e l a t e n t p e r io d i n th e p h o tic r e s p o n s e o f Mya a r e n a r ia * l o u r . Gen. P h y s i o l . , v o l . 1 , p . 657.

14.

1919 The e f f e c t o f te m p e r a tu re on th e l a t e n t p e r io d i n th e p h o tic r e s p o n s e o f Mya a r e n a r i a . l o u r . Gen. P h y s i o l . , v o l . 1 , p . 667.

1y.

. 1920 The p h o to c h e m ic a l n a tu r e o f th e p h o to s e n s o ry p r o c e s s , l o u r . Gen. P h y s i o l . , v o l . 2 , p . B29.

18. —

.«« 1920 I n t e n s i t y and th e p r o c e s s o f p h o to re c e p tio n * P h y s i o l . , v o l , 2 , p . 33 7 .

19

l o u r . Gen.

. — -----1920 P h o to c h e m is try o f v i s u a l p u r p le , I* The k i n e t i c s o f t h e d e c o m p o s itio n o f v i s u a l p u r p le by l i g h t , l o u r . Gen. P h y s i o l . , v o l. 3, p . 1,

20.

1924 P h o to c h e m is try o f v i s u a l p u r p le . Ill* The r e l a t i o n b etw een i n t e n s i t y o f I I g h t and r a t e o f b le a c h in g o f v i s u a l p u r p le , lo u r * Gen* P h y s i o l . , v o l* 6 , p* 7 3 1 .

21*— — — — 1924 I n t e n s i t y d is c r i m i n a t i o n and th e lo u r * Gen* P h y s i o l . , vo l* 6 , p . 355.

s ta tio n a ry s t a t e ,

22* J a h n , T . 1 . and F . C r e a c i t e l l i 1936 The e l e c t r i c a l re s p o n s e o f th e g r a s s h o p p e r u n d e r c o n d itio n s o f l i g h t and d a rk a d a p t a t i o n , lo u r* , C e ll* and Comp* P h y s i o l . , v o l , 12, p . 3 9 . 25.

C ecro p ie. m oth e y e , p . 113*

1939 Hie e l e o t r i c a l re s p o n s e o f th e lo u r* C e ll* and Comp* p h y s io l* , v o l . 1 3 ,

24. r e s p o n s e o f t h e compound

1940 D iu r n a l ch an g es i n th e e l e c t r i c a l e y e . B io l* B u ll* , v o l , 7 8 , p . 4 2 .

2 5 , J a h n , T# 1* and V* 1* W u lff 1942 E l e c t r i c a l a s p e c ts o f a p e r s i s t e n t d i u r n a l rh y th m i n t h e compound ey e o f B y tis c u s f a s o l v e n t r i s * (To a p p e a r i n P h y s io l* Z o o l•) 26.

1941 R e t in a l p i g a e n t d i s t r i b u t i o n i n r e l a ­ t i o n t o a d i u r n a l rhythm i n th e compound eye o f D y tis c u s , p r o c . Soc* Exp* B io l* an d M ed,, v o l . 4 8 , p . 65 3 .

27.

— • - 1941 I n f lu e n c e o f a v i s u a l d i u r n a l rhythm on f l i c k e r re s p o n s e c o n to u r s o f D y tis c u s . Proc* S o c. Sxp* B i o l , an d M e d ., v o l* 4 8 , p . 660*

28.

— -m.. —

------1 9 4 2

A llo c a tio n

o f e le c tr ic a l re sp o n se s

from th e eye com plex o f g r a s s h o p p e r s . Gen* P h y s io l* )

(To a p p e a r i n th e J o u r .

29# K ra u s e , A* C* 1942 The p h o to c h e m is try o f v i s u a l p u r p l e . S y m p o sia, v o l . 7 , p . 23. 3 0 . T a n s le y , K. 1931 R e g e n e ra tio n o f v i s u a l p u r p le , v o l* 7 1 , p . 4 4 2 .

lo u r * P h y s io l* ,

3 1 . W ald, G. 1935 The c h e m is tr y o f t h e v i s u a l p u r p le s y s te m . on Q u a n t i t a t i v e B io lo g y , v o l . 3 , p . 251. 32.

~ 1938 On rh o d o p s in i n s o l u t i o n , 2 1 , p . 795.

1933

D iu r n a l rh y th m s.

Sym posia

l o u r . Gen. p h y s i o l . , v o l .

3 3 . — — —— 1942 V i s u a l s y ste m s and th e V ita m in s A. v o l . 7 , p# 4 3 . 3 4 . W elsh , 1 . H. 123.

B io lo g i c a l

B i o l o g i c a l S ym posia,

Q u a r t. R ev. B i o l . , v o l . 1 3 , p .