THE EEACTION^ TO TACTILE STIMULI AND THE 

 DEVELOPMENT OF THE SWIMMING MOVE- 

 MENT IN EMBRYOS OF DIEMYCTYLUS 

 TOROSUS, ESCHSCHOLTZ. 



BY 



G. E. COGHILL. 

 Studies from the Xeurolosjivul Laboratory of Denison University, No. XXII. 



With Six Figures. 



In 190G I began a series of experiments upon embryos of Rana 

 and Amblystoma with a view to determining whether there is any 

 regularity in the earliest neuro-muscular responses to tactile stimuli 

 in the amphibian embryo. During the season of 1907 these ex- 

 periments were continued upon embryos of Diemyctylus torosus, 

 Eschscholtz (Triton torosus). Although the work of the first year 

 gave interesting results and convinced me that the field of investi- 

 gation was a fruitful one, it was less exhaustive and critical in its 

 methods than the later work has been, and there is no occasion to 

 give an account of it in this connection. It will, therefore, receive 

 no further treatment here and all the data and discussions of this 

 paper will relate exclusively to Diemyctylus torosus. 



These experiments were originally planned for correlated ana- 

 tomical and physiological studies. As an introduction to such 

 work upon Amphibia they form the basis for the anatomical part, 

 since they reveal distinct phases in the development of neuro-muscu- 

 lar response to the most primitive system of cutaneous receptors. 

 But, apart from this significance to pure anatomy and physiology, 

 they are, of themselves, an interesting contribution to the science 

 of animal behavior, for they deal with a most important phase of 

 behavior, namely, its very beginning in the embryo. If, for in- 

 stance, there is any such thing as a ^'simple reflex," such as Sherring- 



The Journal of Comparative Neurology and Psychology. — Vol. XIX, Xo. 1. 



