172 Wortman — Studies of Eocene Mammalia hi the 



\< different; he simply runs out until lie can gather a handful 

 of smaller branches of the opposite tree, and swings himself 

 across the interval with ease. Indeed, the skill displayed by 

 monkeys in climbing surpasses that of any other animal. 



It is of course not now possible to discover just what com- 

 bination of circumstances first led the ancestors of the Primates 

 to adopt an arboreal habit; it may have been for the purpose 

 of greater protection from enemies, it may be that certain 

 kinds of food, such as fruit and nuts, attracted them to the 

 trees, or it may have been both ; but, whatever the cause, it 

 appears certain that this manner of life was adopted very early 

 in their career, and has been responsible for one of the most 

 important structural modifications which they now exhibit. 



Another matter of great interest in connection with the 

 prehensile extremities relates to their probable influence upon 

 the growth of the cerebral hemispheres, as well as the general 

 increase in intelligence in the Primates. No very complete 

 phvletic history can as yet be made out for any existing species 

 of monkeys, but such evidence as is obtainable demonstrates 

 very clearly that the brain has increased in size over and above 

 that found in the earliest forms. In some instances, this 

 increase has been less marked than in others, but there has 

 been, nevertheless, a gradual development of the cerebral 

 hemispheres in all groups of the Primates. In the case of the 

 lemurs the increase has been comparatively small, while in the 

 apes and monkeys it has been relatively great. 



Now, to what causes is it possible to attribute this develop- 

 ment of the brain? A few modern naturalists of note claim to 

 have discovered evidence of an internal perfecting or directing 

 principle, by means of which variations along a given line only 

 are originated and preserved, and which, through the subsequent 

 action of natural selection, forever holds them steadfast in the 

 narrow path of their final development. In any such view of 

 evolution, I find it necessary to express my utter and unquali- 

 fied disbelief. In my judgment, not only is there no evidence 

 in support of such a proposition, but, on the contrary, all the 

 facts of paleontology, as far as they are capable of any inter- 

 pretation, point directly to an opposite conclusion. Such a 

 view of evolution, moreover, presents no advantages over the 

 antiquated doctrine of special creation, which, on account of 

 its inconceivability as well as of total lack of evidence in its 

 support, has long since been relegated to the category of 

 extinct ideas. 



In like manner do I find it equally difficult, and inconsistent 

 with the evidence, to believe in the all-sufficiency of natural 

 selection, as advocated by the Neo-Darwinian school of evolu- 

 tionists. If we had no evidence other than that afforded by 

 the well-known modifications in structure of the cave faunae 



