No. 596] 



EVOLUTIONARY THEORY 



465 



Nageli, C. 1865. Entstehung und Begriff der Naturhistorischen Art. 

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Nageli, C. v. 1898. A Meehanico-Physiological Theory of Organic Evo- 

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Osborn, H. F. 1912. The Continuous Origin of Certain Unit Characters 

 as Observed by the Paleontologist. Amer. Nat., 46: 185-206; 249-278. 

 Apl.-May. 



Osborn, H. F. 1915. Origin of Single Characters as Observed in Fossil 

 and Living Animals and Plants. Amer. Nat., 49: 193-239. April. 



Pearl, E. 1916. Fecundity in the Domestic Fowl and the Selection Prob- 

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Sieveking, H. 1913. Uber der jetzigen Stand der Forschung iiber Eadio- 

 aktivitiit. Natunvissensehaften, I: 129-133. Feb. 7. 



