372 SCIENCE PROGRESS 



degenerate and die. The undifferentiated cell is capable of performing all the 

 vital functions including reproduction by division. With the increase of spec- 

 ialisation all other functions are lost save only the one. Hence in the adult state 

 of the higher animals \vc have myriads of highly modified cells all capable of 

 performing one particular function with remarkable efficiency, but nearly all of 

 which have lost the power of reproduction. After the supply of primitive cells has 

 been exhausted the body cells gradually complete their cytomorphosis and 

 degenerate. When a sufficient number of cells or a group of such as are of vital 

 importance die, the death of the organism as a whole necessarily follows, as there 

 are no undifferentiated cells to make good the loss, and the others, highly 

 specialised already, cannot take on another function. This is assuredly a much 

 more acceptable hypothesis than Metschnikoff's theory of disharmonies. 



The chapter on the doctrine of immortality is practically a review of what we 

 have been accustomed to call the continuity of the germ plasm in the light of 

 recent research. 



The author is very cautious in dealing with the conception of life and 

 apparently reaches no definite conclusion. On the one hand he admits that 

 "the mechanistic explanation is stringently sufficient for most vital processes," 

 but on the other, he points out that three phenomena, viz. organisation, the 

 teleological mechanism, and consciousness, are not yet satisfactorily explained by 

 the mechanistic theory. 



Two or three printers' errors, e.g. " Crustacia " for Crustacea (p. 29), " works " 

 for worms (p. 38), " whech " for which (p. 100), and " Weissman " for Weisman in 

 several places, might well have been avoided in so small a book. The author 

 himself also makes use of one or two words in a somewhat unusual sense — 

 "defines" instead of designates (p. 29), "critic" instead of critique (p. 76), and 

 " designate with " instead of designate by (p. 4). 



The whole book is written in a moderate manner, no rash conclusions are 

 set out, and the views of other writers are treated with consideration. It is 

 remarkably readable and stimulating and, if the system of exchange professors 

 leads to series of lectures such as these, the sooner it is adopted in our universities 

 the better. 



C. H. O'D. 



Animal Life by the Sea-shore. By G. A. Boulenger, LL.D., D.Sc, F.R.S., 

 and C. L. Boulenger, M.A., D.Sc. [Pp. xii + 83, with 91 illustrations.] 

 (London : Country Life, Ltd. Price ^s. net.) 



Few pursuits yield more pleasure than the study of the many animal forms 

 inhabiting the sea-shore, and few are more easily followed. The amateur, how- 

 ever, is constantly encountering difficulties, and needs some book for further 

 guidance. It is to supply such a need on the part of the sea-shore naturalist that 

 the present book has been written. 



The names of the authors are a sufficient guarantee of the soundness of the 

 zoology of the book; but something more than this is needed to appeal to the 

 layman, and we must confess to a slight feeling of disappointment on reading it. 

 The charm and enthusiasm that one meets in the pages of the old favourite 

 Philip Gosse are missing, and the present book is perhaps more for reference than 

 for reading. From this point of view the work is an admirable one, and contains 

 a great deal of the right sort of information within its all too few pages. The 

 illustrations are on the whole very good, though the photograph reproduced in 



