May io, 191 7] 



NATURE 



203 



Prof. Castle has been recognised as one of the 

 most active workers on these lines. A book 

 embodying his outlook after years of teaching 

 and research is sure of a welcome from all who 

 are interested in these matters. The volume is 

 evidently designed more especially for the uni- 

 versity student. It falls roughly into three 

 sections : an introductory portion dealing with 

 theories of evolution and what may be termed pre- 

 Mendelian genetics, a main part treating of con- 

 temporary genetic work, and a final section on 

 human heredity and eugenics. The amount of 

 ground covered involves a condensed treatment 

 of many important questions, and though this 

 need not be a drawback to the student whose 

 reading is supplemented by lectures, it makes it 

 rather a difficult book for the average reader. 



The author has approached the subject almost 

 entirely from the zoological side, and, for a book 

 of the sort, devotes an unusual amount of space 

 to the inheritance of characters in domesticated 

 animals. This part of the work is freely illus- 

 trated by photographs which have generally been 

 w-ell reproduced. But in some cases, as in Fig. 53, 

 an attempt has been made to indicate colour differ- 

 ences in black and white, and the result is not 

 happy. 



Though the space devoted to plants is avowedly 

 brief, ■ the omission of any adequate account of 

 the remarkable phenomena exhibited by plant 

 chimaeras must be regarded as a shortcoming, for 

 it may well be that the principles here involved 

 will turn out eventually to be of much wider 

 application than appears at present. Some of the 

 statements in this section are open to criticism by 

 the botanist, as, for example, that 'which records 

 doubling in. the poppy as recessive to single. The 

 reverse is true of Meconopsis. 



In connection with sex-determination more 

 attention might have been paid to the phenomena 

 associated with gynandromorphs. The extra- 

 ordinarily interesting and suggestive work of 

 Goldschmidt is not even mentioned. 



The best part of the book is that dealing with 

 the effect of selection and the constancy of here- 

 ditary factors. From extensive experirnents on the 

 inheritance of white markings in rats. Prof. Castle 

 has come to the conclusion that the hereditary 

 factors upon which pattern depends may undergo 

 alteration on crossing, thereby becoming either 

 more or less potent in bringing about their 

 peculiar reaction. Plus and minus variants are 

 thus produced which may be isolated by selection. 

 He speaks of the process as one of "contamina- 

 tion," though it is not altogether clear how he 

 supposes it to be brought about. His ideas have 

 been subjected to severe criticism in America, 

 where many geneticists prefer to explain these 

 phenomena on the hypothesis of multiple factors 

 •or of specific modifiers. It is clear that we do 

 not yet understand this type of inheritance, and 

 Prof. Castle's presentation of his case deserves 

 most careful consideration. 



The treatment of eugenics is eminently sane, 

 and most people will probably agree with the 



NO. 2480, VOL. 99] 



conclusion that " we should extend our knowledge 

 as rapidly as possible, but not legislate until we 

 are very sure of our ground." 



An excellent feature is an appendix containing 

 a translation of Mendel's paper, which ought to 

 be carefully digested by every student. A fairly 

 full bibliography concludes the work. This might 

 well be revised in a later edition to include all 

 references to paf>ers mentioned in the text. On 

 p. 208 alone, for example, there are three such 

 references which are not to be fou*nd in the biblio- 

 graphy. 



OUR BOOKSHELF. 



Life and Habit. By Samuel Butler. New edi- 

 tion, wit^;I author's addenda. Pp. x-f3io. 

 (London : A. C. Fifield, 1917.) Price 55. net. 

 We were a little afraid to read " Life and Habit " 

 again after a quarter of a century, lest all the 

 magic might have gone. Perhaps some of it has, 

 for we found tediousness in the criticisms of 

 Darwin-^e.^; in that culminating on p. 260 with 

 the conclusion that a certain sentence from the 

 "Origin of Species" "does not contain, or at 

 any rate convey, any clear or definite idea at all." 

 Butler was sometimes too much preoccupied with 

 his own views ; in this case the meaning of 

 Darwin's sentence seems no conundrum. But 

 the old charm is still in the book — the good 

 humour, the epigrams, the dividing sword, the 

 sincerity, the insight. The new edition seems to 

 differ from that of 1877 only in including four 

 short addenda found among the author's papers. 

 The first and second are biologically interesting; 

 the fourth strikes one as a lapse of good taste 

 which should have been left to blush unseen. 



That Butler's genius gave him insight into evolu- 

 tion problems has been generally, though tardily, 

 recognised. What were the convictions that led 

 him to react so violently from Darwinism? The 

 first was that "there is in every impregnate ovum 

 a bond-fide memory," more than a system of 

 characteristic chemical processes occurring in a 

 characteristic colloidal substratum. By memory 

 he did not mean necessarily conscious memory. 

 The second was that he could not bring himself 

 to believe that the raw materials of evolution, 

 variations to wit, arose by chance, "blind" and 

 "unintelligent." The third was that when a 

 living creature does something often, the fre- 

 quently repeated experience must affect the germ- 

 cells and have results enregistered in them. It is 

 strange that so ingenious a mind never really 

 understood the subtlety of natural selection, the 

 way in which it sifts directively, not randomly, 

 its consistent reference to the -established web of 

 life, and its progressive character. . J. A. T. 



Compressed Air Practice in Mining. By David 



Penman. Pp. vii + 221. (London: Charles 



Griffin and Co., Ltd., 1916.) Price 55. net. 



The first two chapters of this book, dealing with 



the theory of air compression and subsequent ex- 



