162 G. E. COGHILL 



of embryos of Diemyctylus torosus from the earliest responses 

 to tactile stimulation up to the time when the embryo can swim, 

 and showed that there are distinct types of movement which 

 develop in a regular order of sequence till they culminate in 

 locomotion. Later results from studies chiefly upon Amblystoma 

 were presented before the American Association of Anatomists 

 in the Cleveland meeting of 1912 and before the American Philo- 

 sophical Society in Philadelphia, April, 1913. The part of the 

 former report that related particularly to the motor column of 

 the spinal cord was published in this Journal, April, 1913; the 

 report before the American Philosophical Society is abstracted 

 in Science, May 9, 1913 (p. 722). In these communications it 

 has been emphasized that the earlier responses of the embryos 

 under consideration are determined by the nature of the primary, 

 or first reflex arc that becomes demonstrable by histological 

 methods, that the progressive development of this arc determines 

 the order of development of somatic movements and that the 

 final common path of the reflexes stimulated from the various 

 fields as the embryo develops becomes the nervous mechanism of 

 locomotion. 



These earlier presentations of my work have been made as 

 preliminary to a more exhaustive treatment of the growth proc- 

 esses in the nervous system in their relation to behavior, and 

 it is, accordingly, my purpose to make this communication one 

 of a series which will treat in a more complete manner the par- 

 ticular phases of the problem in hand. As the first of such a 

 series, this paper deals with the development of the sensory 

 system of the trunk in its relation to the behavior of embryos of 

 Amblystoma up to the swimming stage. The species used have 

 been A. punctatum and A. opacum, but the latter only rarely. 



