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ARLCO=UREASE is a dry, soluble Powder, active and standardized, 

 prepared after Van Slyke's method and containing the urea-splitting 

 enzyme of the soy bean. 



Samples and literature on request. 



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Yonkers, IN. V. 



IMRORTAIST SOIBNTIRIO BOOKS 



Animal Communities in Temperate America. A Study in Animal Ecology. By Victor Eenest Shel- 



FOHD, Instructor in Zoology in the University of Chicago. 



380 pages, 8vo, cloth: 33.00, postage extra (weight 44 oz.) 



This volume by Dr. Shelford presents the principles of field ecology, illustrated by the more widely distributed 

 animal habitats of the eastern half of temperate North America, and the aquatic habitats of a much larger territory. 

 Six chapters deal with general principles. In several chapters animal communities of lakes, streams, swamps, forests, 

 prairies, and various soils aud topographic situations are considered from the point of view of modern dynamic ecology. 

 A very valuable feature of the book is the three hundred figures of widely distributed animals chosen to represent the 

 chief types of animal commimities and their characteristic modes of life. 



Bullelin of the American Geographical Society, This book is unique in that it is a pioneer of 'its sort and the first serious 

 attempt to treat of the physiology of organisms and of animal communities in such shape aa to serve as an 

 adequate text and reference work for students. 



Artificial Parthenogenesis and Fertilization. By Jacques Loeb, Member of the Rockefeller Institute for 

 Medical Research. 



318 pages, 12mo, cloth: §2.50, postage extra (weight 36 oz.) 



This new work presents the first complete treatment of the subject of artificial parthenogenesis in English. It 

 gives an account of the various methods by which unfertilized eggs can be caused to develop by physico-chemical means, 

 and the conclusions which can be drawn from them concerning the mechanism by which the spermatozoon induces de- 

 velopment. Since the problem of fertilization is intimately connected with so many different problems of physiology and 

 pathology, the bearing of the facts recorded and discussed in the book goes beyond the special problem indicated by the 

 title. -■ tzL's,-k.v;^i±feei5£K'4^-ii;zii/:.-:^^.-Ji-:^^^^ 



Brj7i5A Mc(//<:a/ yournc/.'^The author has gained a world-wide reputation for his achievements inartificial fertilization, 

 and this work shows how, according to his observations, the action of well-known chemical and physical agencies 

 may be^substituted for that of the living spermatozoon. 



THE UNIVERSITY OF CHICAGO PRESS • ■ Chicago, Illinois 



The Baker & Taylor Company, Ntw York Karl W. Hlersemann, Leipzig 



The Cambridge University Press, London, Edinburgh The Maruzen-Kabushlkl-Kalsha, Tokyo, Osaka, Kyoto 



