158 Journal of Comparative Neurology. 



factors which determine the forms of the parts; of the 

 modifications induced by the mechanics of growth during 

 the ontogeny; and, finally and most important of all, 

 of the phylogenetic history. It is this latter point 

 which most often gives the clue to structure, and 

 this is a justification for the recognition of compara- 

 tive anatomy in a scheme of the correlation of sciences for 

 the study of the dynamics and statics of the nervous 

 system. 



A generation ago comparative anatomy in this country 

 was chiefly in the hands of the medical profession, and the 

 medical journals contained many memoirs upon the 

 anatomy of the lower animals, memoirs that are standard 

 sources of information to the biologists to-day. With the 

 development of medical specialties and the advance of 

 specialization in other departments of knowledge, all 

 this is changed and it often happens that the pathologist 

 of to-day, for instance, is acquainted with the normal 

 structure of the organs in the human body, the morbid pro- 

 cesses of which he is investigating, but knows little of 

 their comparative anatomy, histology and embryology. 

 Of course it is not to be expected that under the present 

 conditions pathologists should conduct special researches 

 in comparative anatomy or embryology; nevertheless an 

 acquaintance with the general principles of these sub- 

 jects is indispensable for pathology if this science is to 

 gain a broader and more comprehensive basis. 



How much would be left of the general laws of the 

 science of embryology if all of the facts acquired by the 

 comparative method were stricken out ? And if physi- 

 ology had never availed itself of the opportunities afforded 

 by experimentation upon the lower animals, as a science 



