A. R. MOORE 31 



the action of nicotine in squid is 6 or 7 minutes at 24°C., the con- 

 centration of nicotine being 1,500,000. 



In conclusion the facts presented suggest, {a) that the nerve proc- 

 esses of Lumhriciis terrestris are similar in chemical constitution to 

 the axis cylinders of the medullated nerve fibers of mammals; (b) 

 that the neurons of the earthworm are more limited in their possi- 

 bilities of chemical stimulation; i.e., they are simpler in chemical con- 

 stitution, than the neurons of cephalopods and of mammals. 



