



10 



Time, 



15 



minutes 



20 



25 



Fig. 131. Closure of the pupil of the isolated eel's eye, followed by plotting the move- 

 ment of its margin with a camera lucida. The movements are shown magnified 54 X , 



Time in minutes. 



U- 



2-35 



Ringer 



2;Z0 



-2-05 

 -1-90 

 1-75 

 1-60 

 145 

 1-30 

 1-15 



Acetul choline . . , L ■■ 

 Vmnnnnn Acetylcholine 



1/100.000 Atropine 7100,000 



Vl .000.000 



Red light 



White 



Red 



15 



20 11 



35 



40 



i 



45 



50 



55 



Time, minutes 



Fig. 132. Changes of diameter of isolated eel's iris in Ringer's solution with the 



addition of various drugs. Acetyl choline produces some closure, atropine some 



opening. Light still produces closure after application of atropine. 



Pilocarpine 



Fig. 133. Movements of margin of pupil in isolated iris of Uranoscopus in isotonic 



solution. Pilocarpine produces closure and atropine opening of this pupil whose 



sphincter muscle is innervated by sympathetic nerve-fibres. 



(From Young, Proc. Roy. Soc. B. 107.) 



