CoGHiLi., TJie Reaction to Tactile Sinniili. I05 



system" and dismisses tlic study of specific reactions as impracticable, 

 on account of the '^apparently conflicting" data ; but my work clearly 

 demonstrates that, in response to the stimulus employed in my experi- 

 ments, embryos of Diemyctylus have a veiy definite and regular 

 mode of response, during certain phases of development. In fact I 

 have yet to find the first individual that, through any considerable 

 period, reacts contrary to the mode described in this paper, that is 

 to say, no embryo has yet come under my observation that regularly 

 moves its head toward the side touched when the stimulation is on 

 the head. JSTor have I found a single embryo that, observed for a 

 considerable period, has not fallen under one of the three types which 

 I have here described. 



