560 



Comparative Animal Physiolog^y 



Fig. 207. Effect of acetylcholine (8 parts in 10") on turtle heart. 



ACH 5X10 



ri2 



ACH 7X10 



-II 



ACH 10' 



Fig. 208. Effect of acetylcholine in three concentrations on heart of Venus mercenaria. 



From Wait.^''" 



ACH CL /0-e 



ACH CL 10-'^ 



ACH CL 10-^ 



Fig. 209. Effect of three concentrations of acetylcholine on the heart of the lobster. 



From Welsh.""' 



A'.hlO 



Fig. 210. Effect of acetylcholine (1 in lO'j before and after eserini/ation of the heart of 

 Arenicola. From Prosser and Zimmerman.""' 



