402 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



they articulate with the phalanges. Mr. Carey having 

 agreed with me that those have been produced by me- 

 chanical causes, he alleges that they are not inherited, 

 but are produced by each generation for itself. To 

 this Dr. J. L. Wortman remarks as follows: 



"With reference to Mr. Carey's first proposition 

 that the metapodial crests are produced during the life 

 of each individual by the necessary interaction of parts, 

 it appears to me to be a very simple one indeed. If 

 they are produced, by pressure during the lifetime of 

 each individual, and are not inherited, then clearly we 

 should find the crests absent in new born animals that 

 had never walked, and in which the metapodials had 

 not been subjected to any impact or pressure what- 

 ever. I have taken the trouble to examine a number 

 of such examples in which the distal ends of the bones 

 were entirely cartilaginous, and I find that the keels 

 and grooves are as well developed as they are in the 

 adult animal. I will cite one case in particular in 

 which I happen to know the history completely. Dur- 

 ing the past winter, a young hippopotamus was born 

 in the Zoological Gardens in Central Park, New York, 

 and it was stated to have been a premature birth ; the 

 animal lived but twenty-four hours, and I was informed 

 by the keeper that it never stood upon its feet. An 

 examination of the feet shows that the distal ends of 

 the metapodials are entirely cartilaginous, and in them 

 the keels are as well prefigured in cartilage as they are 

 formed in bone in the adult animal. I have also found 

 the same to be true of new-born rabbits and guinea- 

 pigs. In another case of a young buffalo calf preserved 

 in the American Museum Collection, the distal keels 

 of the metapodials are complete notwithstanding the 

 fact that the epiphyses of all the bones are very im- 



