NATURE 



[July i8, 1918 



methods, in which knowledge was acquired by 

 experience, were admirably suited to the days when 

 engineering practice was largely empirical. To- 

 day, however, a lengthy period of technical train- 

 ing is essential, but it should preferably be preceded 

 by at least one year in the works, and followed 

 by a two or three years' apprenticeship. 

 Technical: training will never make indi'fferent 

 students into good engineers, and able students 

 may succeed without it, but the average man finds 

 it a necessity. The remark that a man must first 

 be an engineer by nature applies equally effectively 

 to all walks of life. 



The author's gravest error, however, is the in- 

 excusable manner in which the requirements for 

 and characteristics of engineers and artisans and 

 of engineers and inventors are confused. Industry 

 has long since lost that individual craftsmanship 

 which distinguishes art; and the parallel drawn 

 between artists and engineers no longer holds 

 good.' In the case of dentists — to which special 

 reference is rnade— the field of work is so broad 

 that a distinction is now being made between the 

 dental mechanic, who learns his trade much as' 

 does the engineering artisan, and the dentist 

 proper, who is frequently university-trained, as is 

 the engineer. Clearly, the author has not fully 

 comprehended the difference now existing between 

 trade education and technical . education for 

 manual workers and for professional engineers 

 respectively. 



The book is written in a very attractive manner, 

 although it is marred by several examples of slip- 

 shod phraseology. We are unable to see in it any 

 adequate result for the four years' research 

 admitted by the author, or the call which 

 prompted him to write it. 



' OVR BOOKSHELF. 



Field Book of Insects. By Dr. F. E. Lutz. Pp. ix 

 + 509. (New York and London : G. P. Putnam's 

 Sons, 1918.) Price 125, 6d. net. 

 The author of this handy little volume offers some- 

 thing of an apology for adding to the large number I 

 of books— -" popular, semi-popular, and unpopu- \ 

 lar '' — on insects, but he has produced a general 

 guide to entomology which will prove uniquely \ 

 valuable to the amateur collector and observer. ^ 

 "I have been governed in the choice of subject- ! 

 matter," he writes, "not so much by what I think I 

 ought to be in a book on insects as by what the 

 public seems to want to know." He gives summar- : 

 ised characters for the discrimination of the various j 

 insectan orders, diagnostic tables for the principal I 

 families, and in some cases also for the genera, I 

 and mentions a number of species — 1400 in all 

 — which may be found commonly in the northern 

 United States, naturally paying especial attention 

 to those of economic importance. On the hundred 

 small plates — many of which are effectively 

 coloured — a' good selection of these species is 

 clearly figured. The result is that the student can 

 scarcely fail to identify, approximately at least, 

 the insects which he captures during an ordinary 

 NO. 2542, VOL. lOl] 



country ramble, while he finds in this volume 

 (which would slip easily into a side-pocket) in- 

 teresting information about their habits and im- 

 portance. 



Although the book deals specially with the 

 North American fauna, it will prove of service to 

 British and European collectors, as so many of 

 the species and nearly all the genera are common 

 to the Eastern and Western continental lands. 

 Nevertheless, a work somewhat on these lines, 

 compiled for the benefit of our own people, would 

 be a most desirable addition to our entomological 

 literature, for it certainly contains " what the public 

 seems to want to know," and "the public" that 

 is mildly interested in entomology has a particular 

 desire for coloured figures which render compara- 

 tively easy the identification of conspicuous insects, 

 like the popular Lepidoptera, to which Dr. Lutz 

 devotes more than 100 pages. A special chapter 

 on galls, with four plates of outline drawings, fur- 

 nishes an introduction to a highly interesting aspect 

 of insect bionomics. G. H, C. 



The Grapsoid Crahs of America. By Mary J. 



Rathbun. (Smithsonian Institution, U.S. 



National Museum, Bulletin 97.) Pp. xxii + 461. 



(Washington :. Government Printing Office, 



1917.) 

 This volume, by an author who has earned a high 

 reputation by previous work on Decapod Crusta- 

 ceans, is part of a systematic treatise dealing with 

 the crabs of the whole of the New World, to be 

 completed in four parts, the main purpose being, 

 to give a brief description, with figures, of each 

 species, together with a detailed catalogue of the 

 specimens in the United States National Museum. 



The work has evidently been prepared with 

 great care. When the author took up the subject 

 the collection under her charge had been partly 

 worked out, but the nomenclature stood in need 

 of revision, and in order to overcome the diffi- 

 culties connected with a correct interpretation of 

 the types of so many' species described by 

 Fabricius, Herbst, de Saussure, the two Milne 

 Edwards, Miers, and others, she spent much time 

 in the museums of Copenhagen, Kiel, Berlin, 

 Geneva, Paris, and London, where not only fresh 

 descriptions and photographs were taken, but 

 arrangements were made for exchanges whereby 

 many co-types and specimens directly compared 

 with types were secured for the American museum. 



The classification adopted is that of Borradaile 

 for the higher groups ; the definitions of families 

 and sub-families are copied or adapted from those 

 given by Alcock. 



Illustrations add greatly to the value of a work 

 of this kind ; the numerous text figures and 161 

 plates, on which examples of nearly all the species 

 dealt with are represented from photographs, 

 deserve the highest praise. 



Now that such an excellent guide is available, 

 it is to be hoped that attention will be directed to 

 the life-histories, which, the author tells us, have 

 not been worked out in more than a dozen 

 American species. G. A. B. 



