June 22, 19 16] 



NATURE 



339 



I W'e read that Darwin's capacity as a mathe- 



\ matician was probably of slow g-rowth ; as an 



undergraduate he did not display any of that 



\ colossal power of work and taking infinite trouble 



' which characterised him later. It surprised his 



friends afterwards that he should have developed 



the patience for making- the laborious numerical 



calculations on which much of his most original 



work was based. 



Prof. Brown's memoir deals with Darwin's 

 scientific work. A leading characteristic is 

 that he was an applied mathematician in the 

 ' strict and older sense of the word. He did 

 not undertake investigations for the interest of 

 the mathematical processes, but for the interest 

 of the phenomena. " Darwin belonged essentially 

 to the school which studies the phenomena by the 

 most convenient mathematical methods. Strict 

 logic in the modern sense is not applied nor is 

 it necessary, being replaced in most cases by 

 intuition which guides the investigator through 

 the dangerous places." When the problem seemed 

 intractable to analysis, he had recourse to 

 numerical methods, and never seemed to hesitate 

 to embark on the most laborious computations 

 which might throw light on the phenomena. In 

 his address to the International Congress of 

 Mathematicians at Cambridge (which is also re- 

 printed in this volume) he referred to his methods 

 in the words : " My own work on the subject 

 cannot be said to involve any such skill at all, 

 unless indeed you describe as skill the procedure 

 of a housebreaker who blows in a safe door with 

 dynamite instead of picking the lock." 



Prof. Brown gives an admirable review of the 

 ground covered by the papers in the earlier 

 volumes, showing the unity of aim throughout 

 all Darwin's work; his memoir will form an 

 excellent introduction for those who wish to 

 enter on a serious study of the papers. 



OVR BOOKSHELF. 



Diseases of Poultry : their Etiology, Diagnosis, 

 Treatment, and Prevention. By Raymond 

 Pearl, Frank M. Surface, and Maynie R. Curtis. 

 Pp. xi + 342. (New York: The Macmillan 

 Company; London: Macmillan and Co., Ltd., 

 1915.) Price 85. 6d. net. 



This interesting and well-illustrated book con- 

 tains twenty-one chapters and a glossary of tech- 

 nical terms. The chief subjects dealt with are the 

 diagnosis of diseases in poultry, avian materia 

 medica, a discussion of the diseases generally 

 found to infect the various organs, poisons, in- 

 ternal and external parasites, tumours, and 

 poultry surgery. 



The book is stated to be a compilation, but it 

 is unfortunate that few other than American pub- 

 lications appear to have been used as sources of 

 information. Thus, the use of catechu for white 

 diarrhoea is ascribed to Salmon, who published in 

 191 3, while the treatment was originally set forth 

 by Fantham and employed in England in 1910. 

 NO. 2434, VOL. 97] 



Mention should be made of the very clear and 

 concise exposition of poultry hygiene that is given 

 in the second chapter. Were the instructions 

 detailed therein to be carried out universally there 

 is no doubt that nine-tenths of the losses now 

 experienced among poultry would be saved. The 

 short account on materia medica for the poultry- 

 man is simple, sound, and eminently practical. 

 Many useful hints on the administration of drugs 

 used in combating such parasitic infections as 

 tapeworms are also given. 

 i The chapter on the recognition of external para- 

 j sites and the eradication of diseases, such as scaly 

 ! leg and depluming scabies, is ably written, and 

 I the section on skin diseases and their cure is ade- 

 j quately treated. When dealing with diseases 

 I of the reproductive organs an interesting account 

 of the various abnormalities .observed in eggs, 

 ; their causation and prevention, is given, attention 

 . being directed to the abnormalities of practical 

 I importance in egg-production and marketing. 

 There is also a chapter on white diarrhoea, in 

 ; which the chief American views on the various 

 forms of this disease, coccidial and bacillary, are 

 set forth. 



We have pleasure in recommending the book to 

 the attention of the practical poultrv-keeper. 



F. 



.4 Generation of Religious Progress. Edited by 

 G. Spiller. (Issued in Commemoration of the 

 2 1st Anniversary of the Union of Ethical 

 Societies.) Pp.151. (London : Watts and Co., 

 1916.) Price 15. net. 

 A COLLECTION of articles by nine contributors. 

 Sir H. H. Johnston, dealing with science and 

 religion, eloquently sketches the progress of 

 thought from simian times, and has interesting 

 things to say about family affection in apes and 

 savages, and about development of ancestors into 

 local deities. He thinks that "religion, as the 

 conception of a heavenly being, or heavenly beings 

 ... concerning themselves greatly with the 

 affairs of man, has been abolished [or, later, "put 

 entirely in the background "] for all thoughtful and 

 educated people by the discoveries of science " ; 

 but he shows reverence for the teaching of Jesus, 

 and believes true Christianity is primarily con- 

 cerned with the service of rrian. 



In the remaining essays in the volume Mr. 

 Alfred Martin describes the history and methods of 

 the higher criticism ; Mr. William Archer writes on 

 religion and democracy, with Asia and Europe as 

 the fount of each respectively; Miss Margaret 

 McMillan, in her section on woman's mission, is 

 advanced, but sensible, as always ; Mr. Joseph 

 McCabe, on the humaner spirit, mentions reforms 

 in the hours of labour, in the sanitation of prisons, 

 in Parliamentary representation, and claims that 

 not science, but humanistic idealism is the 

 greatest phenomenon of modern times; Prof. J. S. 

 Mackenzie writes on educational ideals, Mr. C. T. 

 Gorham on the moral ideal, and Mr. G. Spiller on 

 the future of religion. 



