THE 



AMERICAN NATURALIST 



Vol. L. November, 1916 No. 599 



THE EVOLUTIONAEY SIGNIFICANCE OF THE 

 OSMOTIC PEESSURE OF THE BLOOD 1 



GEORGE G. SCOTT 

 College of the City of New York 



The facts of comparative anatomy, embryology and 

 paleontology form the tripod of evidence on which rests 

 to a great degree the validity of the doctrine of evolution. 

 Accepting the doctrine of evolution as a working hypoth- 

 esis has resulted in clearing up puzzling problems in the 

 above named departments of biological inquiry. At the 

 present time, more attention is being paid to physiological 

 than to morphological problems. In physiology, the 

 great emphasis is placed on mammalian problems with 

 especial reference to man himself. Now if the mammals 

 are the product of a long process of evolution from simple 

 ancestors, it follows that not only has there been a mor- 

 phological evolution, but also the present complicated 

 functions of the higher animals have evolved from the 

 simpler processes of primitive ancestral forms. In order 

 to understand the significance of particular physiological 

 facts, we must therefore view the matter in the light of 

 evolution. It is not essential that all needful evidence be 

 at hand to make perfectly clear the significance of the 

 higher physiological activity. Indeed, it is well worth 

 while at times to state clearly any of our problems in the 

 evolutionary form and arrange the evidence accordingly. 



>Eead by title before The American Society of Naturalists, Philadel- 

 phia, Dec, 1914. 



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