REVIEWS 523 



spite of the apparent correspondence between reduction divisions and segrega- 

 tion, that the chromosomes are the sole effective instruments in heredity. He 

 points out that it follows from Mendelian results that characters, or rather the 

 elements of characters, are indivisible units, and that variation therefore is 

 either the addition or omission of one or more factors. Of the causes of this 

 addition or omission we are still ignorant, but one question arises which Prof. 

 Bateson does not discuss, namely, whether all additional factors are derived 

 from an original unchanging stock. This conclusion would seem to follow from 

 his argument that variation is the consequence of asymmetrical divisions in the 

 germ-cells. It is with his brief remarks on Adaptation that the present writer 

 most emphatically disagrees. He asserts that each new character is formed in 

 some germ-cell of some individual at a particular time. If such a character is 

 beneficial or injurious it will survive or disappear, but that the occurrence of 

 the variation is guided ever so little by the needs of adaptation there is not the 

 smallest sign. It will be time to consider this assertion when Prof. Bateson 

 or any Mendelian has investigated the heredity of any one adaptive character. 

 At present they are unaware of the difference between adaptive and specific 

 characters ; in fact they do not understand adaptation. The problem of species 

 which they investigate has nothing to do with, or at least is entirely distinct 

 from, the problem of adaptation. 



It must not be supposed from the above criticisms that the present writer 

 fails to appreciate the value of Prof. Bateson's book, which must be acknow- 

 ledged to be the most important that has appeared for a long time in relation 

 to general Biology. Every one interested in the general problems of the science 

 must be sincerely grateful for such an excellent exposition and survey of the 

 Mendelian doctrine of heredity, the value of which is increased by the full 

 bibliography. No one can study evolution or heredity now without a knowledge 

 of Mendelism, and this book will doubtless take its place among the classics 

 of biological literature. 



J. T. Cunningham. 



Outlines of Bacteriology (Technical and Agricultural). By David Ellis, 

 Ph.D., D.Sc, Lecturer in Bacteriology and Botany to the Glasgow and 

 West of Scotland Technical College, Glasgow. [Pp. xii + 262.] (London : 

 Longmans, Green & Co., 1909. Price 7s. 6d. net.) 



IN the Preface it is stated that this book is intended to serve as an introduction 

 to Bacteriology in all its branches, though more attention has been bestowed on 

 that aspect of the subject which deals with technical and agricultural bacteriology. 



The scheme is an ambitious one, but nowhere are more than the rudiments of the 

 subject dealt with, except perhaps in the first five chapters in which the mor- 

 phology and general biology of the bacteria are adequately considered. We 

 doubt, therefore, if the student will find sufficient for his needs unless he desire 

 merely a superficial survey of the subject. 



After a general biological introduction to the bacteria and certain higher forms, 

 chapters are devoted to sterilisation, the bacteria pathogenic to animals and 

 plants, thermogenic, chromogenic, photogenic, and sulphur and iron bacteria, 

 the preservation of foods, nitrification, fermentation and its industrial applications, 

 and lastly sewage and its disposal. 



The plan of the book and its sectional contents have been well conceived, but 



