5 i 4 SCIENCE PROGRESS 



cannot fail to be impressed with what, for want of a better term, may be called 

 the instability of the species. Races from different parts present considerable 

 differences, and mutation constantly occurs in the general population. The 

 chapter on the cytological basis of the mutants is very interesting and reveals 

 the fact that various mutants have different numbers of chromosomes ranging 

 from 14 to 28. It is noteworthy that the number 28 occurs in CE. gigas and 

 certain of its offspring, and it almost appears as if the large size of the plant is 

 the result of the possession of the double number of chromosomes. A whole 

 series of the mutants appears to result from an irregular meiotic distribution 

 of the chromosomes. Indeed, in general the mutants in Oenothera appear to be 

 very closely related to the number of chromosomes in their nuclei and often 

 produced by irregularities in their distribution, such irregularities occurring during 

 the reduction mitoses. This bears out what we meant by the instability of the 

 species, for it seems as if the equilibrium of the nucleus can be upset fairly readily. 

 The Mendelians have claimed that mutation is but another exemplification of 

 Mendelism; but we think the author is justified in claiming that it is quite distinct. 

 The two phenomena of hybridism and mutation are, of course, intimately related, 

 and although the former sometimes seems to lead to an increase of the latter the 

 two are nevertheless distinct. 



After a brief account of the kinds of mutations the author concludes : " As 

 regards the ultimate nature of mutations, we are therefore inclined to look upon 

 them as the result of various types of change in the nucleus — (1) morphological 

 changes (a) in number, (b) in shape and size of chromosomes, or in the arrange- 

 ment of their substance ; (2) chemical or functional changes in {a) whole chromo- 

 somes or (b) portions of particular chromosomes, by which a function may be 

 modified or lost ; (3) two simultaneous mutations may occur through mismating 

 of the chromosomes in two pairs, so that each germ-cell receives both members 

 of one pair; (4) changes may perhaps occur in the mysterious karyolymph or gel 

 which forms the groundwork of the nucleus." The Mendelians come in for a 

 certain amount of well-deserved criticism, for, as the author remarks apropos of 

 their constant attempts to express almost everything in terms of the one hypo- 

 thesis, " the truth is that Mendelism is a theory of inheritance, and as such is 

 not adapted to deal with the question of origins at all." 



It is, on the whole, a clearly written, interesting, and well-illustrated book. 



C. H. O'D. 



A History of British Mammals. By G. E. H. Barrett-Hamilton and 

 M. A. C. Hinton. [Parts XV. and XVI., 1914, and Part XVII., 191 5.] 

 (London : Gurney & Jackson. In parts, 2s. 6d. net.) 



The previous part (XIV.) of A History of British Mammals contained a notice 

 of the death of E. Wilson, the friend of the author and artist responsible for many 

 of the useful plates that illustrate the work. He was with Captain Scott on his 

 ill-fated expedition to the Antarctic regions. Sadly enough, the next part (XV.) 

 contains a notice of the death of Major Barrett-Hamilton himself while on a 

 scientific inquiry into the whale fisheries of the Southern seas. It was fortunate 

 that Mr. M. A. C. Hinton of the British Museum had worked in close association 

 with Barrett-Hamilton and was able to carry on the work so tragically interrupted. 

 These three parts indicate clearly enough that the very high standard set by 

 the previous parts will be maintained, and a more uniform result will be obtained 

 than might otherwise have been expected. They deal with British mice ; and 

 although perhaps one may deplore the multiplication of subspecies and varieties, 



