196 THE ZOOLOGIST. 



Variations in Animals and Plants. By H. M. Vernon, M.A., 

 M.D. Kegan Paul, Trench, Triibner & Co., Ltd. 



This book constitutes vol. lxxxviii. of the " International 

 Scientific Series," and is devoted to a question which goes to the 

 root of the most prevalent conception of evolution at the present 

 era, for, as Wallace has remarked, " the foundation of the Dar- 

 winian theory is the variability of species." This variability 

 has been hitherto recorded in a somewhat loose or impressible 

 manner by different naturalists, whose observations have formed 

 most of the bricks used in current theories and conclusions. The 

 investigation has recently been pursued, and principally by friendly 

 advocates, by an altogether different method, and we are now 

 beginning to understand the teachings of a mathematical biology. 

 This is likely to attain vast results, for, although few naturalists 

 care for, and most naturalists dislike, figures, we have recently 

 read in an American publication that, in the opinion of Dr. G. B. 

 Halsted, about one in two hundred persons in America possessed 

 some sort of mathematical genius, a mental condition probably 

 not confined to that country. The work done by what we pro- 

 pose to call mathematical biologists is the careful measurements, 

 weighings, &c, of long series of a single species, found in a 

 special environment and under special conditions ; the study of 

 these by a mathematical process, and the results given in mathe- 

 matical formula, thus providing for evolutionists a valuable 

 material for biological statistics. Dr. Vernon has largely drawn 

 on these data, and has thus focused very much valuable material 

 in a well-arranged way in his discussion of the subject; in fact, 

 his volume is a storehouse of collected information of facts 

 obtained by workers who have followed this process. The 

 author, of course, has also views of his own, to which we can 

 only refer the reader, and we will conclude with a quotation with 

 which many will agree: — "In spite of all that has been written 

 to account for the almost universally present adaptation which 

 we see in animate nature, there is still a lingering doubt in the 

 minds of many men as to the entire adequacy of the explanations 

 hitherto offered." 



