OETHOGENESIS AS OBSERVED FEOM PALE- 

 ONTOLOGICAL EVIDENCE BEGINNING IN 

 THE YEAE 1889^ 



DR. HENRY FAIRFIELD OSBORN 



American Museu.\[ of Natural History 



1. The Origin of Species 



The Origin of Species is now clearly understood in 

 the hard parts of invertebrates and of vertebrates, and 

 there is little to be added as to the modes of mechanical 

 evolution. No chances or experiments are tried by Na- 

 ture. The process is continuous, adaptive, mechanically 

 perfect in every Mutation of Waagen. As shown in 

 actual observations by all close students of vertebrate 

 and invertebrate morpholog}' .during the last fifty-two 

 years, and as summed up in the remarkable contribution 

 of DArcy Wentworth Thompson (1917) on "Growth 

 and Form," animal mechanisms compete with each other 

 in close analogy to humanly made machines— automo- 

 biles, tj'pewriters, aeroplanes. Consequently, while Na- 

 ture is constantly standardizing her machines through 

 individual competition and producing flocks of birds and 

 shoals of fishes which are so precisely alike that animals 

 of the same age, sex, environment and heredity show no 

 perceptible variation, she is also frequently substitut- 

 ing more perfect and more adaptable machines and dis- 

 carding older and less adaptable ones, exactly as man is 

 doing in the case of his automobiles, his tj'pew^r iters, and 

 his aoro|)lanos. Thus tlio naturalist and the paleontolog- 



