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THE AMERICAN NATURALIST. [Vol. XXXVII. 



on the averages of large series of measurements of hybrid offspring, 

 but is very probably vitiated by the occurrence of artificial partheno- 

 genesis so easily produced in the case of echinoderm eggs. Another 

 series of experiments cited by Vernon in support of his view is hardly 

 more convincing. It consists in experiments made by Ewart with 



"Mendel's Law" is treated as a law of "hybridization " only, its 

 profound significance as a general law of heredity being unnoticed, 

 while the Galton-Pearson " Law of Ancestral Heredity " is treated as 

 the law of heredity. To many biologists the evidence for the Men- 

 Pearson law to be thus lightly brushed aside. It also raises a strong 

 presumption against Vernon's idea of a heritage gradually changing 

 during the ripening of the sexual products. 



Part III, contains a brief survey of a familiar field. Natural 

 selection is recognized as the efficient agency in evolution. Adaptive 

 variations are discussed at some length and the evidence for and 

 against their inheritance are considered. Environment is regarded 

 as directly inducing germinal variation. W. E. C. 



PHYSIOLOGY. 



Von Fiirth's Comparative Chemical Physiology of the Lower 

 Animals. 1 — Perhaps the most important general advance made by 

 physiology in the last ten years has been the inclusion of the lower 

 animals within its field of research. Just as anatomy was immensely 

 illuminated by a thorough investigation of the structure of the lower 

 forms and thus became truly comparative, so physiology will gain a 

 clearer and more certain insight into life processes by a study of 

 these where they occur in greatest simplicity. What has already 

 been done in this direction especially from the chemical standpoint 

 is scarcely accessible to the student except through the original 

 sources of publication for ever so excellent a book as Verworn's 

 General Physiology passes over this subject most superficially. Von 



Fischer, 1903. 8vo.. xiv +670 pp. 



