( B98 ) 



1 502 14608 88234 156190 9!' 

 where R represents tlic rhonibotope thai is Ihe sum of the nine forms 



starting- from 



1 (20) (-20) (100^ (80) (Oü) (40) (20) 



-i/,0 =ï'., =/, -,0/, +45/, -120/, +210/, , 

 by applying 



(20A-) (2) (2) (2; 



i, = (10 k 4- 8)9 7', + (10 k -f- 7)., 7'2 + -f (! O /t-)9 7_i 



for k = 5, 4, 3, 2, 1 after some calcnlation tiie resnJt 



(2) (2). (2) (2) 



394713550 (Ti + 7' i) -f 410820025 {TI + 7'_2) 



4- 422709100 (7'3"^ + 7'^_^_3) + 430000450 (7^^^ + T% 



4- 432457640 Tf\ 

 which after substitution of the relations given above leads back to 

 the identity 



(20) 9 (2) 



Ts =10 n . 



Physiology. — ''The electric response of the eye to stimulation by 

 liylit (It various intensities'. By W. Einthovkn and W. A. 

 Jolly. (Communication from the Physiological Laboratory of 

 Leiden). 



Ahhough the electrical response of the eye to stimulation by light, 

 which was discovered by Holmgren has since been studied by 

 numerous observers, there has not so far been undertaken a systematic 

 investigation of the electromotive changes which are caused by 

 stimuli of very varying strength. Such an investigation, however, 

 can as we hope to show, contribute not a little to our comprehension 

 of the retinal processes. 



We have in our work employed exclusively isolated frogs' eyes. 

 We have been enabled oji the one hand by means of the string 

 galvanometer, wliich for the retinal currents may be regarded as the 

 most sensitive instrument available, to record and measure very 

 weak electromotive forces, such as ai'e evoked by light of extremely 

 low intensity ; on the other hand we have tried by a suitable 

 system of lenses to concentrate light of as great intensity as possible 



