REVIEWS 353 



Particularly interesting are the parts on the inheritance of a number of characters 

 in the fruit-fly Drosophila, whose name has become a veritable household word to 

 all biologists owing to the classical investigations of Prof. Morgan and his 

 co-workers. This information, accessible to the specialist in a long series of 

 papers from Morgan's laboratory, is here put within the reach of all and in such a 

 form that it can be comprehended by the beginner. Its clearness is helped in 

 large measure by a fine series of figures, many reproduced from actual photo- 

 graphs. 



It may be that a study of biological problems tends to produce a conservative 

 attitude which looks with suspicion upon new theories, or perhaps it is that a 

 knowledge of the failure of the many great theories of the past to provide a 

 complete explanation of inheritance results in a very healthy scepticism of a 

 panacea. It may be both. Whatever it is, however, when we read that " with 

 the discovery of this mechanism (Mendelism) I venture the opinion that the 

 problem of heredity has been solved," and further, " So I repeat, the mechanism of 

 the chromosomes offers a satisfactory solution of the traditional problem of 

 heredity," we admire the courage but doubt the wisdom of the prophecy. It is 

 the privilege of a pioneer to work with unbounded enthusiasm in the future of his 

 theories, and when this is backed by such substantial results as in Morgan's case 

 no other course is open save to treat it with profound respect. When, however, 

 we consider that other good workers have been led to an entirely opposite 

 opinion, we are forced to the conclusion that a verdict of " non-proven " more 

 precisely states the case. 



The book is very useful to the student, be he beginner or more advanced, and 

 one that can be read with profit and considerable pleasure by all interested in 

 biology. It is perhaps significant that at the time of writing the supply in this 

 country is exhausted. C. H. O'D. 



On Growth and Form. By D'Arcy Wentworth Thompson. [Pp. xvi + 793, 

 with 408 illustrations.] (Cambridge : at the University Press, 191 7. 

 Price 21s. net.) 

 It is of course obvious upon reflection that if animals utilise inorganic materials, 

 as they do to an enormous extent in their skeletal structures, such substances 

 necessarily conform to the ordinary physical laws. Further, that animals being 

 in the main solids or semi-fluid must conform to the ordinary laws governing the 

 relation of surface to volume, of surface tension and so on. Few, however, have 

 troubled to trace to what an extent these laws of physical science apply in the 

 animal kingdom, and with a somewhat characteristic distrust of mathematics and 

 physics the biologist has been content to 'leave such questions alone. In so 

 doing a wide field of research has been left almost untrodden, and as this volume 

 will soon show, a field that has already yielded a number of interesting results and 

 promises a rich harvest to future investigators. The criticism applies particularly 

 in this country, and Prof. Thompson deserves thanks for bringing to notice a 

 large number of the phenomena to which these mathematico-physical laws apply. 

 Although in the main dealing with animals, their application to the plant kingdom 

 is also dealt with, as for example in the height of trees, the arrangement of cells, 

 the formation of intercellular partitions, and Phyllotaxis. 



It is of course in the skeletal structures that we find the most striking examples 

 of the working of these laws, and such parts as horns, tusks, shells, and spicules 

 receive full treatment. It is a pity that the book was published too early to 

 include a reference to the recent interesting work of Dendy and Nicholson on the 



