234 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1938 



imperils the safety of the species, by undermining its vitality, ham- 

 pering it in endeavoring to escape from enemies, and in obtaining 

 food. 



Closely associated with, and perhaps hardly separable from 

 hypertrophy, is the development of excessive "ornament", whether 

 it be the plumage of birds of paradise, or peacock's, or in the 

 "excrescences" of bony structures in the forms of horns, or out- 

 growths on the body, found in the case of so many extinct types of 

 animals. Sir Arthur Woodward, one of the foremost paleontologists 

 of our time, has drawn special attention to phenomena of this nature, 

 which he interprets as the final "flare-up" of the lamp of life before 

 extinction. Having attained to their maximum size and weight, all 

 further surplus material for growth was expended on "ornamenta- 

 tion." And this is a view which will probably find general acceptance. 



Let me pass now to two closely related aspects of animal life which 

 afford convincing evidence, in support of my contention, that living 

 bodies, whether of animals or plants, are self-regulating in the matter 

 of the growth, both of their external and internal organs. These 

 aspects are furnished through what are known as phylogeny and 

 ontogeny. 



The history of the evolution of the elephant forms a pageant which 

 held the stage for some 30,000,000 years. As an illustration of 

 "phylogeny" it is well nigh complete. But I can do no more, here, 

 than select a few of its more interesting phases, showing its trend. 

 The complete story has been told by the late Prof. Henry Fairfield 

 Osborn, the greatest authority of his time on this theme. He dis- 

 tinguished four main lines of descent, and 300 species, displaying a 

 most marvelous series of gradations in the evolution of the tusks, and 

 the great molar teeth, a progressive series, accompanied by an equally 

 progressive increase in size. 



Reduced to its simplest terms, and most essential features, then, 

 it begins with Moeritherium, a semiaquatic animal discovered some 

 years ago by my old friend and colleague, the late Dr. C. W. Andrews, 

 in the Eocene deposits of the Fayum. In general appearance it may 

 be likened to the pigmy hippopotamus. Attention is more especially 

 to be directed towards its teeth, of which there were 36 in all. The 

 upper jaw, on each side, bore three incisors, one canine, three pre- 

 molars, and three molars. The lower jaw had but two incisors and 

 no canine. The outer pair of the upper incisors, it is to be noticed, 

 were large and directed downward, while the outer lower incisors, 

 large and chisel-shaped, were directed forward and slightly upward. 

 The gap between the cheek teeth and the incisors of the lower jaw 

 was but slight, and this is a fact to be borne in mind, in view of what 

 follows. 



