166 SCIENCE PROGRESS 



between its birth and the next conception is known, the sex of the succeeding child 

 can be foretold. In forecasting the sex of children by this method he claims to 

 have had 97 per cent, of successes. So also the sex can be determined at will, by 

 allowing conception to take place only when one or other ovary ovulates. 



The author has collected a quantity of evidence in support of his theory, much 

 of which is apparently quite sound ; but cases like the following leave one some- 

 what sceptical. "Lloyd's Weekly Neivs, October 26, 1902, quoting the New York 

 Herald, says that . . . Signora M. Giannetta, of Nocera, near Naples, had fifty-nine 

 boys and three girls. She had triplets on eleven occasions, quadruplets on three 

 occasions, sextuplets once, besides eleven children in single births " (p. 144). 



The thick sprinkling of italics and black type is irritating, as are at times the 

 dogmatic statements, e.g. "by no other theory can the similarity of such twins be 

 explained" (p. 133). 



The chapter on greater resemblance to one parent shows an entire lack of 

 knowledge of heredity : we are told that though one spermatozoon conjugates 

 with the egg-nucleus, the greater or less resemblance of the child to the father 

 depends on the number of additional spermatozoa which enter the ovum. 



We hope that the book will lead to more careful collecting and recording of 



cases which shall show whether the ova from one ovary do actually always give 



rise to children of the same sex. 



L. DONCASTER. 



The Development of the Chick : an Introduction to Embryology. By Frank 

 R. Lillie. [Pp. xii + 472.] (Henry Holt & Co., New York, and George 

 Bell & Sons, London, 1908. Price 16^. net.) 



The aim of this volume is to provide the elementary student with a plain account 

 of the development of the chick, which, for obvious reasons, has always been 

 a favourite type among teachers of embryology. But although this work is 

 intended primarily for the beginner, as an introduction to the subject, it contains 

 much that is of interest to the advanced student and the original investigator. 

 The account given refers almost exclusively to Gallus, but it has been found 

 necessary to fill in certain gaps in the ontogenetic history by descriptions of other 

 birds. Mammalian embryology is not discussed at all, and no attempt is made to 

 deal with the comparative side of embryological science, but the author is careful 

 to point out that this omission does not imply any want of appreciation of this 

 branch of the subject, but is due to the conviction that the elementary student is 

 not in a position to understand the problems involved. It is, however, open to 

 question whether in a book intended for the beginner it might not have been 

 better to illustrate the principles of embryology by references to types belonging 

 to more than one class of vertebrate in preference to giving an exhaustive account 

 of the developmental history of one. 



There is a short introduction dealing with the cell theory, the recapitulation 

 theory, the physiology of development, embryonic primordia, the general 

 characters of the germ cells, and the polarity and organisation of the ovum. 

 In discussing the recapitulation theory the author does well to point out that 

 von Baer repudiated the principles involved in the law so often associated 

 subsequently with his name. Meckel appears to have been the first to advance 

 the doctrine that the higher organisms pass through the definitive stages of the 

 lower, but the theory was not fully elaborated until after the publication of 

 The Origin of Species, when Fritz Muller and Ernst Haeckel stated it in what 

 is essentially its present form. 



