December 26, 1912] 



NATURE 



459 



to the discredit of the subject. In Prof. Tower's 

 chapter this tendency shows itself chiefly in his 

 references to tlie faulty methods of other investi- 

 gators (Kammerer, Woltereck, Sumner, and 

 others are mentioned in this connection), 

 although no clear statement is given as to where 

 the fault lies. The objections may be sound, but 

 it is scarcely fair thus to impugn the accuracy of 

 the work of others without making it quite clear 

 in what the inaccuracy consists. 



In some of the other chapters the dogmatic 

 attitude appears rather in the form of leading the 

 reader to believe that problems are completely 

 understood when, as a matter of fact, many 

 points with regard to them remain obscure. This 

 is exemplified in Prof. Castle's short account of 

 sex-determination in Rotifers and Daphnids, and 

 more seriously in some of Prof. Davenport's state- 

 ments about the inheritance of certain characters 

 in man. That the statements are made in a more 

 definite form than is justified by the known facts 

 is doubtless explained by the necessity of making 

 them clear and impressive to an untrained 

 audience, but it is unfortunate that in preparing 

 the lectures for publication more care was not 

 taken to differentiate between facts which are 

 absolutely known, and inferences which do not as 

 yet admit of rigid proof. 



In conclusion, it should be mentioned that the 

 last two chapters include a couple of slips which 

 might mislead the reader : on p. 277 diabetes 

 insipidus (which appears to be confused with the 

 common diabetes) is correctly placed among ab- 

 normalities which appear to be dominant, but it 

 is stated that two normal parents may have defec- 

 tive children ; and on p. 286 the statement is made 

 with regard to recessive abnormalities that "two 

 affected parents have exclusively normal children," 

 where affected children is, of course, meant. 



(2) Prof. Greil's book is of a very different char- 

 acter. It is an attempt to show that all the pheno- 

 mena of development, inheritance, and sex- 

 determination can only be properly considered 

 from the point of view of epigenesis. The word 

 "epigenetisch " appears on almost every page, 

 and much dialectical skill is expended in showing 

 that cases in which some form of predetermination 

 appears to be the natural explanation are really 

 epigenetic in character. The motto of one of the 

 chapters — 



"Was du ererbt von deinen Vatern hast, 

 Erwirb' es, um es zu besitzen," 



is the central theme of the book — that the germ 

 only receives inherited tendencies, and that these 

 cannot be studied apart from the manner and con- 

 ditions of their development. In general, this is 

 3/ course true, but in his treatment of it the 

 NO. 2252, VOr.. C;t] 



author will seem to many readers to carry his 

 thesis to extreme lengths. Since the develop- 

 ment of an inherited tendency is a physiological 

 process, it should theoretically be possible to in- 

 duce a similar physiological process without any 

 inherited tendency ; therefore the inheritance of 

 acquired characters must be possible in certain 

 cases. Although in some cases the presence of a 

 specific sex-chromosome causes the individual to 

 become of one sex, in the absence of a sex- 

 chromosome influences which bring about the 

 same physiological condition in embryonic life will 

 also cause it to be of that sex. Telegony must 

 exist, because the bearing of young of a different 

 breed must cause the mother to become "in a 

 certain sense a hybrid." The whole hypothesis of 

 Mendelian factors must be given up because it 

 savours of preformationism rather than epigenesis. 

 To summarise chapters in sentences of this sort 

 is perhaps scarcely doing the author justice, but 

 they give a fairly accurate idea of his attitude. 

 The book suffers from the absence of head- 

 ings to chapters or paragraphs ; there is no 

 table of contents and an entirely inadequate index, 

 so that it is very diflficult to find out in what part 

 of the book any given subject is treated. The 

 style also is overloaded and difficult to follow. 

 The last 130 pages are devoted to a critical 

 I account of theories of heredity, closely printed in 

 exceedingly small type. L. Donc.aster. 



PHOTOGRAPHIC ANNUALS. 

 (i) The British Journal Photographic Almanac 



and Photographer's Daily Companion, 191 3. 



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York: George Murphy, Inc., 1912.) Price 75 



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