458 



NATURE 



[December 26, 1912 



scientific text-books dealing with the practical side 

 ol pottery, though France, Germany, and the 

 United States have .each in turn shown great 

 activity in this special department of work. 



We must, however, confess to a little disap- 

 pointment with the work, for, instead of a 

 reasoned, adequate discussion of the many prob- 

 lems which beset the potter such as we had a 

 right to expect, it proves to be a reprint, almost 

 without alteration, of a series of articles that 

 ■ appeared rather more than a year ago in the 

 columns of a trade journal. Perhaps it is for 

 this reason that the volume resembles far too much 

 the mere note-book of a diligent student, valuable 

 in its way as a record of salient points and of the 

 latest published work, but more valuable to the 

 writer than to the reader. 



We may mention as an example the opening 

 paragraph of chapter ii. : — 



" There are numberless varieties of clay, but it 

 \ixc !] may roughly be divided into ball clay, china 

 cla)', and fireclay ; or, in other words, plastic clay, 

 non-plastic clay, and refractory clay." 



This is certainly very curious information for a 

 potter, considering what a large part the ordinary 

 surface clays of all countries have always played, 

 and still play, in practical work. It is only the 

 modern English earthenware manufacturer who 

 could possibly conceive that such a statement was 

 even approximately true. 



On p. 13 we find the statement that "Two 

 properties of clay — plasticity and cleavage — are 

 of prime importance to the potter." Plasticity we 

 understand, but that the cleavage of clay has any- 

 thing to do with the potter is certainly not proved 

 in the pages of the book. 



One might criticise in the same way the chapters 

 dealing with "glazes" and "enamels," where a 

 number of statements are made as if with 

 authority, though, to say the least, they are 

 exceedingly dubious. 



In the same way the chapter on industrial 

 diseases does not merit its place, for if it were 

 a true statement of the facts of the case the 

 manufacturers have no defence to offer, whereas 

 it is well known that there are the greatest prac- 

 tical difficulties in adopting the solution of the 

 problem recommended, viz., the use of lead sili- 

 cates of low solubility in dilute acid mixtures. Mr. 

 Stephenson remarks that "the problem is one of 

 ways and means, the chemistry of the subject 

 being fairly simple." Certainly, for this is 

 only another way of saying that the theory 

 is very simple, but the practice happens to be 

 difficult. 



W. B. 

 NO. 2252, VOL. go] 



TWO BOOKS ON HEREDITY. 

 (i) Heredity and Eugenics. A Course of Lectures 

 Summarising Recent Advances in Knowledge in 

 Variation, Heredity, and Evolution, and its 

 Relation to Plant, Animal, and Human Improve- 

 ment and Welfare. By William Ernest Castle, 

 John Merle Coulter, Charles Benedict Daven- 

 port, Edward Murray East, William Lawrence 

 Tower. Pp. vii + 315. (Chicago: University 

 of Chicago Press ; London : Cambridge L'ni- 

 versity Press.) Price los. net. 

 (2) Richtlinien des Entwicklungs- iind Vererbungs- 

 problcms. By Dr. Alfred Greil. Zweiter Teil : 

 Anpassung und Variabilitat, Ererbung und 

 Erwerbung, Geschlechtsbestimmung. Pp. iii-i- 

 364. (Jena : Gustav F'ischer, 1912.) Price 

 10 marks, 

 (i) " T T EREDITY and Eugenics" consists 

 X J. of a series of lectures delivered 

 at Chicago in igii by five of the best-known 

 American students of the subject. It deals with 

 plants, animals, and man, and is intended as a 

 popular exposition of recent advances of our 

 knowledge of heredity. The lecturers had evi- 

 dently not consulted each other with regard to 

 the parts of the subject to be dealt with by each, 

 with the result that there is some overlapping, 

 but in a book intended for those who have made 

 no serious study of the problems involved, this is 

 not a serious disadvantage. All the chapters are 

 simply and clearly written, and the book is well 

 illustrated with excellent figures. In general the 

 cases chosen are well suited to the purpose, and 

 for the untrained reader the book will give a clear 

 idea of the present state of our knowledge and of 

 its bearing upon practical problems. 



The student who has attempted to keep abreast 

 with recent work will find very little that is new 

 to him ; everything has been already published 

 elsewhere, usually in an accessible form. To the 

 trained biologist the long chapter by Prof. Tower 

 will probably appear the most interesting ; it is in 

 parts difficult to follow, but gives a very useful 

 summary of his large work on variation in Chryso- 

 melid beetles, which to many is probably know-n 

 only from reviews and abstracts. 



The book as a whole appears to us to suffer 

 from one rather serious defect — the dogmatic 

 style in which most of the chapters are written. 

 For a popular audience it is doubtless necessary 

 to be as definite as possible, and to avoid undue 

 emphasis on apparent exceptions which are really 

 easily explicable. But the writers of this volume 

 seem to carry this principle to lengths which may 

 be absolutely misleading, and to confuse fact and 

 inference in a way which almost inevitably tends 



