INTRODUCTION. 5 



instead of being concentrated and occurring in cataclys- 

 mal fashion as, for instance, in nervous or mental disease 

 in the human subject. Thus, when an animal changes 

 the aquatic for a terrestrial habitat, with the disuse of 

 aquatic sense organs and their substitution by those fit for 

 terrestrial environment, we have practically an example of 

 the pathological method in the atrophic process occurring 

 in the conducting tracts of the sense organs that fall into 

 disuse. Perhaps we might also compare the hypertrophy 

 of the cervical cord in the sea-robin, or that of the vagal 

 lobes in the carp to the hypertrophies occurring as a 

 response to increased function in pathological processes. 



The very fact that the natural experiments in the nerv- 

 ous systems of the lower animals are spread out in time 

 gives the method of comparative neurology a particular 

 value, indeed a value not possessed by other methods of 

 investigation in mental and nervous life. For, the terms 

 of the series of the evolutionary process modifying the 

 reactions and structure of the lower forms of the nervous 

 system being extended over great periods of time 

 and taking place exceedingly gradually, the integral 

 phases of the process are obtrusively unfolded. Whereas 

 in disease of the human subject or pathological mani- 

 festations induced in an individual organism the process 

 occurs so rapidly that its serial phases are run together 

 and the progression of the terms of the process eludes 

 one's grasp. 



I would emphasize the importance of comparative 

 neurology as a metlwd of research in an organization of 

 sciences for the investigation of the phenomena of con- 

 sciousness and their physiological concomitants. This 

 department of science from this standpoint should be 

 turned into account toward the solution of problems of 



