INTRODUCTORY. 13 



the same, and the action of food and poison produces 

 results in which there are few points of difference. Of 

 course, when we infer from the facts observable in the 

 study of animal life that similar facts will be observ- 

 able in human life as well, we have to exercise due 

 caution. It is here that the acumen of a scientific mind 

 is exercised to the fullest degree; we are liable to error, 

 and our results are perhaps tentative, and must be 

 viewed as such, but no one can doubt the suggestive- 

 ness and consequent utility of these studies. Just 

 as our knowledge of comparative anatomy and physi- 

 ology has been essential to a proper understanding of 

 human anatomy and physiology, so the few facts we 

 at present possess concerning human racial develop- 

 ment receive significance when examined by the side 

 of a similar but far more extended array of facts 

 drawn from a study of animal racial develop- 

 ment. 



If, then, it be true that we have before us a small 

 but increasing mass of evidence regarding the laws of 

 racial change, is not this evidence worthy of our 

 closest study? Is it not at least as worthy as the 

 study of the politics of the hour which absorbs so 

 much of our best energies; for what are the petty 

 combinations of parties, or even those temporary 

 associations of individuals, which aim at a common 

 or national policy, by the side of the health and the 

 capacity of that race of which we are but passing 



