i;2 SCIENCE PROGRESS 



of them is made out. This is, indeed, a welcome step, for the nomenclature and 

 proportions of Mendelian results are complicated enough, and a certain amount of 

 unnecessary complexity is removed when these two concepts are discarded. 



Prof. Morgan is an out-and-out believer in his theories, and seems quite pre- 

 pared to regard the Mendelian hypothesis as capable of explaining the inheritance 

 of any or all characters. Some results are quoted as supporting certain interpreta- 

 tions, but to one not immersed in Mendelism it is not entirely satisfactory to find 

 that when according to theory the expected ratio in a count of nearly 3,000 was 

 15:0:1, the result obtained was 22 : 3 : I. If these extensions of Mendelian pro- 

 portions are capable of mathematical statement, and are going to produce figures 

 that are of some significance, and capable of application to other problems, one 

 would certainly hope for a closer correspondence between predicted and actual 

 results. One further point appears open to criticism : in parts the book is very 

 difficult to read and follow. This may follow from joint authorship, or more 

 probably from a laudable intention not to make the book too long and at the same 

 time include all the necessary information. 



Apart from this, however, the work is an excellent one, and one for which the 

 reader will have much to thank the authors. It is well printed and illustrated, 

 and contains a useful bibliography. The plea in its introduction that the study of 

 heredity should not be confined to the expert, as it tends to be at the present 

 time, but should form part of the working equipment of every biologist, is one that 

 will be heartily endorsed in any school of biological thought, and this kind of 

 book goes far to aid the production of that very desirable result. In our opinion 

 it is perhaps the most valuable contribution that has been made to such literature 

 in English since the translation of Mendel's original papers in 1900. 



C. H. O'D. 



The Embryology of the Honey Bee. By J. A. Nelson, Ph.D. [Pp. v + 282 

 with 95 text figures and 6 plates.] (Princeton: Princeton University Press. 

 London : Humphrey Milford, Oxford University Press, 191 5.) 

 MUCH has been written on the bee from many different aspects. Certain points 

 in or parts of its embryology have been worked at by such well-known zoologists 

 as Butschli and Kowalevski, and more recently by Blochmann, Petrunkewitsch, 

 Nachtsheim, and Dickel, yet only one comprehensive account has been given, 

 namely that by Battista Grassi in 1884 in a somewhat obscure Italian publication 

 Good as this account was, it is quite obvious that the whole problem was ripe to 

 be tackled again in the light of the general advances that have been made in our 

 knowledge of insect embryology. Considerable improvement in methods of 

 microscopical preparation enables the difficulties in technique inherent in the 

 investigation of the embryology of an insect to be more successfully surmounted. 

 The present volume is an attempt, and a very successful one, to remedy this 

 deficiency in our knowledge of the bee. The various changes from the un- 

 segmented egg onwards are carefully and tersely described and the main points 

 dealt with in the description illustrated. The illustrations themselves call for 

 note as they are beautifully drawn and reproduced, and show clearly that it is not 

 necessary to rely on the ordinary half-tone process for reproducing sections. 



The difficulty of interpreting many of the phenomena in the formation of the 

 germ layers and embryonic membranes is very great, for as Weismann long ago 

 pointed out, the ontogeny of the insecta is more distorted and ccenogenetically 

 degenerate than perhaps in any other group of animals. Hence the value of 

 carefully recorded and well-illustrated accounts of these occurrences such as we 



