7 i4 SCIENCE PROGRESS 



a. A Textbook of General Embryology. By Prof. William E. Kellicott. 



[Pp. v + 376, with 168 illustrations] (London : Constable & Co., 1914. 



Price \os. bd. net.) 

 /a Ou tlines of Chordate Development. By Prof. William E. Kellicott. 



[Pp. v 4- 471, with 185 illustrations.] (London: Constable & Co., 1914. 



Price \os. 6d. net.) 

 ALL students of biology must have felt the want of a textbook of embryology 

 wherein they could find the facts and theories of this most important branch of 

 their study clearly set out in an elementary manner. Perhaps in no other part 

 of biology is the need of a reliable work more great, and this in a field that has 

 progressed markedly in recent years and which lends itself admirably to a dis- 

 cussion of many important theories. As a rule embryology is relegated to 

 the end of a general textbook, and then treated but indifferently with scant 

 regard for modern work. Here are two volumes that go far towards remedying 

 this state of affairs, and in both the requirements of the student appear to have 

 been constantly borne in mind. 



a. The title of the first is misleading, for it is rather an introduction to em- 

 bryology than a general embryology. About two-thirds of the book is concerned 

 with the accounts of cells, cell division, maturation, and fertilisation, and the 

 remaining part to cleavage, the processes of differentiation, heredity, and sex 

 determination, the blastula, gastrula, and the formation of the germ layers. 

 Embryology is generally preceded by, or, at any rate, accompanied by, studies 

 in general biology, and much of the ground covered in the first part of the 

 book is dealt with in the ordinary textbook, and might, we think, have been 

 considerably shortened with advantage. It deals largely with problems from a 

 cytological point of view. The room thus gained could have been profitably 

 devoted to histogenesis, organogeny, foetal membranes, ccelom formation, and 

 many other important embryological problems. It is just these last questions 

 that are not usually well treated in most elementary books. This, however, is 

 but a criticism of the scope and title of the present volume. 



The various chapters are easy to follow and well illustrated, and the serious 

 student who wishes to follow up any point in greater detail will derive much 

 help from the short bibliography given at the end of each of them. The tables 

 here and there throughout the book are useful. 



b. This book in part fills up the gap noted in the preceding, and gives an 

 account of the development of Amphioxus, the frog, the chick, and the early 

 development of a mammal, including also a brief account of the germ cells and 

 fertilisation. It is a valuable addition to the elementary textbooks, and is of use 

 to the student of biology and to the student of medicine as an introduction to 

 the more detailed study of human embryology. Again, the author is to be con- 

 gratulated on the clearness of his style and the aptness of the illustrations. 

 Prof. Kellicott is in no way to blame for the extraordinary muddle in the 

 volume sent for review. No less than eight pages (pp. 122, 123, 126, 127, 134, 135, 

 130, and 131) are reintroduced at various points, to the exclusion of eight pages 

 of reading matter, with the result that about twenty-six pages of the book are 

 quite useless. It is hard to see how such carelessness could be confined to one 

 copy, and it is to be hoped that the publishers will take steps to see that 

 similarly marred copies are withdrawn from circulation. 



The two volumes read together form a sound introduction to the cytological 

 aspects of the earliest stages of embryology and the latter stages in the chordate 

 types mentioned. C. H. O'D. 



