NA TURE 



[May 3, 1906 



ing on wood are concisely described ; but the principal 

 part of the work, and by far the most important, 

 deals with the colour sensitising of emulsions, and the 

 applications of such sensitised emulsions to the produc- 

 tion of negatives in the many methods of dealing with 

 and reproducing colour that are now in vogue. 



The applications of the newer sensitisers are de- 

 scribed in many scattered communications, and often 

 with very little discrimination between the practically 

 useful and the merely theoretically interesting. Mr. 

 Klein states that he has included only those that have 

 passed the test of time and been found to be 

 thoroughly practical. It is in this that the value of 

 the work lies, and we think that it would have been 

 better to have restricted the volume to this aspect of 

 the subject. The occasional references to the under- 

 lying scientific facts will not help the practical man, 

 nor would they if they were free from the errors that 

 now disfigure them. A volume of practical instruc- 

 tions is not the place for a page or two of chemical 

 equations or the expression of theoretical views that 

 have often been called in question. However, these 

 occupy but little space, and scarcely interfere with the 

 use of the book as a strictly practical manual. 



Der Gegensatz zwischen geographischer und nicht- 



geographischer Variation. By Karl Jordan. Pp. 



59 ; with 73 figures in the Te.xt. (Leipzig : W. 



Engelmann, 1905.) 

 The present treatise affords an excellent example of 

 the light that may be thrown on questions of biological 

 interest by the scientific use of entomological data. 

 Dr. Jordan here presents a valuable resume of some 

 of the most important results of the elaborate investi- 

 gation of the chitinous sex-organs of insects, more 

 particularly the Papilios and Sphingidae, carried on 

 by him for many years past at the zoological museum 

 at Tring. These researches, the detailed results of 

 which have already appeared in the pages of " Novi- 

 tates Zoologies," are of high interest, not only to 

 entomologists, but also to all students of the methods 

 of evolution. 



It must, however, be confessed that the author's 

 interpretations are less acceptable than his facts. 

 Starting from the position that " species " have a 

 real objective existence, he endeavours to show that 

 new species could only have arisen from geographic- 

 ally isolated variations, not from variations occurring 

 side by side with the parent form. The main fact on 

 which he relies is that while " individual " or 

 " seasonal " variation of forms inhabiting the same 

 locality is never accompanied by a variation in the 

 sex-organs (with the single known exception of 

 Papilio xiithus), the diverse geographical forms of a 

 species are in very many cases found to be distinct from 

 one another in sex-organs as well as in aspect. There 

 is thus a correlation in the latter case which does not 

 exist in the former, and which seems to the author to 

 warrant the conclusion that these geographical forms 

 only can occupy the position of incipient species. 

 Some of the obvious objections to this view are dealt 

 with by Dr. Jordan, others are left unnoticed. 



A slight inaccuracy occurs on p. 177, where a 

 figure of Byblia goetzius is said to represent B. 

 ilithyia, while the true B. ilithyia bears the legend 

 B. anvatara ; both mistakes being repeated in the 

 text. A more serious matter is the absence of any 

 detailed reference to Mr. G. A. K. Marshall's work 

 on this genus and his remarkable discoveries in the 

 genus Precis. Some special recognition of these 

 should have found a place, even in a treatise of 

 general nature like the present. It will be gathered 

 from what has been said that Dr. Jordan's conclusions 

 are open to criticism. There can, however, be no 



NO. 1905, VOL 74] 



doubt as to the value of the researches so ably carried 

 on by himself and others in connection with the ample 

 material of Mr. Rothschild's museum at Tring. 



F. A. D. 

 Butter-making on the Farm and at the Creamery 

 By C. W. VValker-Tisdale and T. R. Robinson. 

 Sixth edition, revised and enlarged. Pp. 162. 

 (London : Office of the Dairy World, 1906.) Price 

 2S. 6d. net. 

 We import into the United Kingdom perhaps twice 

 as much butter as we make, and pay twenty millions 

 yearly for it. Some, at least, of these millions would 

 have been saved to the agricultural industry if our 

 farmers and dairymen had given as much intelligent 

 study to the principles of butter-making as, for 

 instance, the Danes have done. Unfortunately, how- 

 ever, in such matters as the use of centrifugal cream- 

 separators, the employment of pure bacterial cultures 

 for "starters," and the general organisation of the 

 industry, we did not lead the way ; we were content 

 to follow, and that, too, with somewhat halting foot- 

 steps. Even now the small butter-maker is often a 

 sad empiricist. If cleanliness, for example, is an 

 article of faith with him — and frequently it is not — 

 he holds it as a dogma, not as reasoned knowledge. 



The little book under notice may help in the re- 

 covery of some of those lost millions. It gives an 

 outline of approved present-day practice in butter- 

 making, though it does not purport to offer much in 

 the_ way of theoretical explanation and discussion. 

 Mainly it is an account of how best to conduct the 

 operations of a small modern dairy. It is practical 

 and simple ; well suited for the elementary dairy- 

 student, for the farmer's son who wishes to know 

 something more than mere rule-of-thumb work, and 

 for the private maker who supplies his own house- 

 hold from his own cows. The first few pages deal 

 with the design, construction, and equipment of the 

 dairy. Then cream is considered, and its separation 

 and " ripening " are described, after which we pass 

 to the churning and subsequent operations. A number 

 of simple arithmetical examples are worked out to 

 illustrate various points that arise. The last thirtv 

 pages deal, briefly and in a more technical manner, 

 with the operations of a fully-equipped creamery, 

 including " pasteurisation " and refrigerating. 



The book does not profess to be much more than a 

 useful note-book and practical guide, but as far as it 

 goes it is excellent. C. Simmonds. 



The Deinhardt-Schlomann Series of Technical Dic- 

 tionaries in Six Languages: English, German, 

 French, Italian, Spanish, Russian. By Kurt Dein- 

 hardt and Alfred Schlomann. Vol. i. The Machine- 

 Elements and Tools for Working in Metal and 

 Wood. Together with an Appendi.x, edited by P. 

 Stiilpnagel. Pp. 403; 823 illustrations. (London: 

 Archibald Constable and Co., Ltd., 1906.) Price 

 5^. net. 

 This volume is the first of a series intended to aid 

 engineers and others in reading technical works in 

 any of the principal modern languages. Terms of 

 general importance only are included ; they are 

 classified into subjects and many are accompanied bv 

 an explanatory sketch. Formulae and symbols, serv- 

 ing as they do the purpose of an international language, 

 are introduced wherever possible. The translations 

 have been tested in workshops and offices in the various 

 countries represented ; so the work ought to prove of 

 service in reading technical literature. The convenient 

 pocket size of the dictionary, the systematic arrange- 

 ment of its matter, and the full alphabetical index of 

 words in each of the six languages should gain for it 

 a sphere of usefulness among technical students. 



