INACTIVITY OF PHYSIOLOGY. 1 65 



of the nascent organism — it will easily be seen that they 

 all admit of purely physiological investigation. And yet 

 till very recently many of them were never closely studied, 

 and consequently the processes of evolution have very often 

 been regarded as something altogether enigmatical and 

 peculiar, and even in some respects miraculous and super- 

 natural. So that even yet many distinguished naturalists 

 hold that the phenomena of evolution are beyond the limits 

 of human knowledge, and are only explicable by the as- 

 sumption of supernatural forces. 



This curious situation, reflecting as it does a somewhat 

 unpleasant light upon the present status of our science, 

 must be laid to the charge of modern Physiology. As I 

 have already had occasion to remark, the Physiology of our 

 day pays no attention either to the functions of evolution 

 or to the evolution of the functions. With praiseworthy 

 energy it has, it is true, exerted itself to perfect as far as 

 possible the knowledge of certain groups of functions, to 

 which an exact mathematical and physical treatment is 

 directly applicable {e.g. the Physiology of the sense-organs, 

 of muscular movement, of the circulation of the blood, etc.). 

 But, on the other hand, it has paid but little attention to 

 many important groups of functions, to which this exact 

 method is not applicable. Among the latter are the choro- 

 logical and oecological functions, many psychological pheno- 

 mena and correlations of growth, and especially the most 

 important of those functions of evolution which we have just 

 enumerate*! — that of Heredity and Adaptation. Our present 

 knowledge of these two most influential physiological 

 functions of evolution has been almost entirely acquired 

 by means of morphological, not physiological research, 



