138 BIOLOGICAL LECTURES. 



The evidence of his vast physiological powers, as shown in 

 his works, are in obvious correlation with his progressive char- 

 acters, such as the upright position and all the correlated modi- 

 fications like the sigmoidal outline of the back, the huge bipedal 

 less, the differentiation of the hands and feet. The obvious 

 correlation of his works also with the size of the brain and 

 shortening up of the lower face, and other retrogressive char- 

 acters, as they are correctly diagnosed by several authors, nota- 

 bly Cope and Minot, make up a paradox which is insoluble as 

 long as evolution is looked upon as uniform in its action. 



In types terminating phylogenetic series, however, such inter- 

 mixtures often occur on a smaller scale. These are not general- 

 ized, but highly specialized creatures, and notwithstanding their 

 retrogressive modifications, they are necessarily the highest in 

 position or grade, as determined by the facts of succession in 

 time and genetic position. Man, like one of these terminals, 

 is retrogressive in essential structures, and, like one of these 

 also, is separable from his nearest congeneric relatives, through 

 the change of law which has converted morphic retrogression 

 into physiological progression. The brain, although larger, is, 

 when compared with that of the human embryo and those of 

 the young of other mammals, plainly arrested in development, 

 as demonstrated by Cope and Minot. It maintains, in its 

 proportions to the mass of the body, the general characters of 

 the embryos of the Mammalia, but has nevertheless differen- 

 tiated in intimate structure and evolved into an organ of such 

 enormous and novel powers that its functional work has 

 become distinct qualitatively, as well as infinitely greater quan- 

 titatively, than that of the animal brain. 



The disregard of researches in comparative ontogeny and 

 phylogeny has also led most investigators of the Darwinian 

 school to believe in the uniformity of action of the laws of 

 evolution, an error that has had far-reaching consequences. 

 Thus Poulton, recognizing that the sudden appearance of ani- 

 mal types in geologic strata was opposed to the Darwinian 

 theory of the slow accumulation of differentials through natural 

 selection, and in order to reconcile the facts with this theory, 

 has assumed that there must have been in existence a vast 



