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SCIENCE 



[N. S. Vol. XXIX. No. 739 



eral judgment as to the men whose work he 

 describes. These judgments and characteri- 

 zations are occasionally rather naively ex- 

 pressed, but the reader is not often inclined 

 to take exception to them, though in certain 

 instances one must do so. For example : 

 The somewhat extended reference to Ehren- 

 berg's work on the protozoa and the very brief 

 mention of Stein is hardly consistent with the 

 fact that Ehrenberg's work, though extensive, 

 was inaccurate and as a whole made no 

 such valuable contribution to our knowledge 

 of this group as did Stein. Kichard Bert- 

 wig's influence upon the progress of proto- 

 zoology has hardly been second to that of 

 Biitsehli. In the chapter upon classification 

 no emphasis is laid upon the recognition of 

 the sponges as clearly distinct from and 

 sharply contrasted with all the other metazoa. 

 In the discussion of advances in cytology no 

 mention is made of the evidence that the male 

 and female parents are equipotential hered- 

 ity, nor is there any reference to the work of 

 Richard Hertwig, Schaudinn and others upon 

 the presence and behavior of generative and 

 vegetative chromatin in the cell, though these 

 subjects are surely as important as recent 

 studies of cell-lineage and regeneration 

 which are mentioned. One wonders if the 

 author's confidence that vitalism is a wholly 

 mistaken conception (p. 181) is justified. Are 

 psychic phenomena chemical and physical? 



The descriptions of the men and their work 

 and place in the progress of biology are not 

 so vivid as they are, for example, in Poster's 

 "History of Physiology," but this doubtless 

 is in part due to the greater scope of the book 

 and its necessarily briefer treatment of each 

 man and his period. The treatment impresses 

 one not as masterful, but as faithful, and in 

 general sound. In its reference to modern 

 workers, American students receive dispro- 

 portionate mention, but in a volume designed 

 for American readers, this is perhaps not un- 

 natural. 



The second part, dealing with the doctrine' 



' Theory might be a better word, for the word 

 doctrine carries with it, not logically but actually, 

 a little of the flavor of the word dogma. 



of evolution, is not so satisfactory as Part I. 

 The author might have been more successful 

 in his attempt to condense into brief state- 

 ment the essential features of the theory. 

 He might well have included reference to iso- 

 lation as a factor in evolution, and perhaps, 

 even in so condensed a treatment as this, 

 organic selection might be mentioned. The 

 presentation of Mendelism (p. 316) would 

 hardly be clear to any one not already familiar 

 with the subject. The statement (p. 389) 

 that " sexual selection is almost wholly dis- 

 credited by biologists " is of course a mistake. 

 Probably all recognize its past importance 

 among human kind, and some believe that it 

 will in time become of greatly increased im- 

 portance in human evolution. 



A few inaccurate statements, and some of 

 doubtful truth, might well be modified in a 

 second edition. Weismann's theory of hered- 

 ity was presented in his essays upon heredity 

 some years before the appearance of his vol- 

 ume " ' The Germ Plasm ' published in 1893." 

 Is it true that " Davenport, Tower and others 

 have made it clear that species may arise by 

 slow accumulations of trivial variations, and 

 that, while the formation of species by muta- 

 tion may be admitted, there is still abundant 

 evidence of evolution without mutation?" It 

 seems, on the contrary, increasingly probable 

 that fluctuating variations do not form a 

 basis for the evolution of new species. It is 

 difficult to see the author's meaning in his 

 statement (p. 404) that " neither mutation 

 nor natural selection is a substitute for the 

 doctrine of the continuity of the germ plasm," 

 or in the statement (p. 405) that "the body 

 cells are not inherited " ; and we can not but 

 object to the form of the statement (p. 406), 

 that " natural selection presides over and im- 

 proves variations arising from mutation," 

 and to the last phrase in the sentence (p. 316). 

 " In this country the experiments of Oastle, 

 Davenport and others with animals tend to 

 support Mendel's conclusion and lift it to the 

 position of a law." Sexual selection in the 

 sense now accepted, though not in Dar- 

 win's usage, has no relation to the " law 

 of battle" (p. 413). In view of evidence 

 presented by Poulton in his address at 



