6g2 SCIENCE PROGRESS 



species. The value of these accounts is much enhanced by maps indicating 

 geographical distribution and the many beautiful illustrations that accompany 

 them. There is perhaps one fault that can be found with this part of the book, 

 and that is the classification. The book is professedly the work of field naturalists, 

 but more attention might have been paid to the works of Lydekker and Pocock. 

 The differences between the Tregelaphin£e and Antelopinae are not made 

 sufficiently clear, and the positions assigned to the Hartebeest and the Oryx are 

 not in accordance with recent anatomical and palasontological research. 



The volumes form valuable works of reference on many points, and are well 

 worthy of a place on the bookshelf of naturalist and sportsman alike. 



C. H. O'D. 



Mimicry in Butterflies. By Prof. R. S. Punnett, F.R.S. [Pp. vii + 188, 

 with 16 plates.] (Cambridge: at the University Press, 1915. Price 15s. 

 net.) 

 General reader and biologist have long been familiar with the phenomenon of 

 certain species of butterflies reproducing the wing pattern of other species not 

 closely related to them, and thereby differing markedly from more nearly related 

 species, and sometimes even from other individuals of their own species and sex. 

 The problem of this resemblance has occupied a great deal of attention since the 

 theory of natural selection was propounded, and, indeed, it has often been cited as 

 a good illustration of the working of the theory itself. The explanation most 

 usually given was that some of these strikingly coloured butterflies were distasteful 

 or even poisonous, and that by mimicking such forms other and harmless species 

 would obtain a certain immunity from the attacks of their enemies. In other 

 words such cases were considered as striking instances of protective adaptation. 



Prof. Punnett in the present volume has given a very useful account of this 

 and allied phenomena with references to a number of the most striking examples, 

 and the well-executed illustrations serve to bring home the main facts in a very 

 clear manner. It is, as far as we know, the most concise and accessible account 

 for the ordinary reader. The various difficulties in the way of accepting the usual 

 explanations are fully dealt with, and it is concluded that, although natural selec- 

 tion may conceivably play some part in the preservation of the mimicking species 

 when they arise, it cannot have helped to produce them — a criticism that has 

 been levelled against natural selection in other fields than the present one ; and, 

 indeed, it is difficult to imagine how the first steps, of necessity rough ones, towards 

 the model could have any selective value. Or, if they had, why such exact repro- 

 duction of the markings should have been required in order to preserve the mimic 

 as we find in several species, for example, in Alcidis agathyrsus and Papilio 

 laglaizei. Furthermore, as the author points out, although it is usually assumed 

 that the agents exercising this selection are birds, yet satisfactory confirmation of 

 this statement is lacking. 



If natural selection is not sufficient to account for mimicry, and it must 

 be admitted that Prof. Punnett makes out a very strong case against it, what 

 is the explanation ? Here, unfortunately, the book is not so satisfactory, for, 

 as the author himself admits, " Though suggestions have been made as to the 

 lines along which an explanation may eventually be sought, it is not pretended 

 that the evidence is yet strong enough to justify more than suggestions." It is, 

 perhaps, to be expected that solution should be sought in the direction of 

 " Mendelism," and reference is made in this connection to the coat colours of mice, 

 rats, and rabbits. But, as is admitted, it is a far cry from these semi-domesticated 





