28 



NA TURE 



[November lo, 1892 



As regards the figures that accompany the work itself, 

 it is a matter for regret that they cannot be commended. 

 Few objects are more difficult to draw or require more 

 skill in their delineation than do the shells of mollusca, 

 and the amateur is rarely able to do them justice. The 

 want of finish in the present instance is all the more 

 noticeable from the contrast they afford to the rest of the 

 " get up " of the work, which is admirable. 



These shortcomings are not thus dwelt on in any cap- 

 tious spirit, but are pointed out in the friendly hope that 

 a future edition of the work may shortly be forthcoming, 

 in which the defects of the present one, compiled under 

 great difficulties and at much disadvantage, may be 

 made good and a really complete catalogue result. 



(BV)2. 



OUR BOOK SHELF. 



The Framework of Chemistry. Part I. By W. M. 



Williams, M.A. (London : George Bell and Sons, 



1892.) 

 This is the first part of a book which has been specially 

 written as a supplement to the oral lessons and experi- 

 mental demonstrations given by a teacher. It is 

 intended to contain nothing but what is absolutely neces- 

 sary to give definite and precise impressions regarding 

 the salient points of the lessons, all details relating to 

 laboratory manipulation being omitted. The more im- 

 portant introductory facts, divested of theoretical con- 

 siderations, are first discussed, then come " atoms and 

 molecules," treated in an elementary fashion and leading 

 the way to the explanation of the use of symbols and 

 formulae. 



How the system adopted by the author will work out 

 can only be ascertained when the other parts are to hand. 

 So far as the information in the present volume goes, it 

 is to a great extent useful and clearly stated. 



Objection may be taken to the classification of solutions 

 as mechanical and chemical, for, were it for no other 

 reason, it is still a disputed point whether any solution 

 may be considered a mixture. 



The concise style of the book lends itself to incomplete 

 statements. For instance, to say that one of the oxides 

 of carbon " contains exactly twice as much oxygen as the 

 other," is hardly accurate ; a constant quantity of carbon 

 is essential to the accurate concepiion of the facts. The 

 most serious blunder made by the author lies in the 

 confusion of force and energy. This is manifest in state- 

 ments involving the conversion of " chemical force " into 

 an •' equivalent amount of heat " or of " electrical force," 

 and culminates in the assertion that " Force, like matter, 

 cannot be destroyed." 



The Beauties of N attire, and the Wonders of the World 

 we Live In. By the Right Hon. Sir John Lubbock, Bart. 

 M.P., F.R.S. (London : Macmillan and Co., 1892,) 

 So many writers of the present day adopt a pessimistic 

 tone that a pleasant impression is alwaj s produced by 

 Sir John Lubbock's genial and imperturbable optimism. 

 In the present volume he undertakes to show how many 

 sources of interest men might find in the world around 

 them, if they would only take the trouble to train them- 

 selves to appreciate the scientific significance of ordinary 

 facts.^ fHe begins with a study of animal life, and has 

 much that is fresh and suggestive to say about various 

 aspects of the subject. Then there are chapters on plant 

 life,' woods and fields, mountains, water, rivers and 

 lakes, the sea, and the starry heavens. The volume is 

 written in the clear, frank style with which all readers of 

 Sir John Lubbock's books are familiar, and it ought 



NO. 1202, VOL. 47] 



to do much to foster among the class to which he appeals 

 habits of careful and exact observation. His readers have 

 the satisfaction of knowing that of the many things they 

 may learn from him none will afterwards have to be 

 unlearned. 



Algebra for Beginners. By H. S. Hall and S. R. Knight. 



(London: Macmillan & Co. 1892.) 

 This work is intended as an "easy introduction " to the 

 author's " Elementary Algebra for Schools," and, besides 

 being treated on lines similar to those of the last-mentioned 

 book, is published in a cheaper form. The idea throughout 

 seems to have been to present the beginner with the 

 practical side of the subject, and with this intention the 

 examples are made as interesting as such examples can 

 be. The usual sequence has not here been strictly 

 adhered to ; but a beginner will find that he will still be 

 able to reach the " as far as quadratic equations" limit. 

 It is needless to say that the explanations are stated in 

 clear and simple language, while the examples are all 

 new. That this book will be widely used is undoubted, 

 for it will form an excellent forerunner to the more ad- 

 vanced one referred to above. 



Introduction to Physiological Psychology. By Dr. 



Theodor Ziehen. Translated by C. C. van Liewand Dr. 



Otto Beyer. (London : Swan Sonnenschein and Co. 



1892.) 

 In reviewing the book of which this is a translation 

 (Nature, vol. xliv, p. 145), we pointed out that such a 

 book was badly wanted in English. We are glad, there- 

 fore, to welcome a translation of Dr. Ziehen's work, which 

 will serve well as an introduction to the new science of 

 physiological psychology. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 viamiscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.\ 



The VolucellcE as Examples of Aggressive Mimicry. 



An interesting point in the Volucellce as examples of aggressive 

 mimicry is the fact that they were first used to support the 

 teleological theories of an earlier day, and were subsequently 

 claimed by natural selection. Thus Messrs. Kirby and Spence 

 speak of them (Second Edition, 181 7, vol. ii., p. 223) as 

 affording "a beautiful instance of the wisdom of Providence in 

 adapting means to their end ; " and after describing the resem- 

 blance of the flies to the bees, they continue, " Thus has the 

 Author of nature provided that they may enter these nests and 

 deposit their eggs undiscovered. Did these intruders venture 

 themselves amongst the humble-bees in a less kindred form, 

 their lives would probably pay the forfeit of their presumption." 

 In this theory of Providence it is hard to see where the bees 

 come in. In 1867, A. R. Wallace published an article on 

 " Mimicry and other Protective Resemblances among Animals," 

 which was in 1875 republished in his "Essays on Natural 

 Selection." In this essay (p. 75 of the volume) he spoke of 

 this interpretation as the only case in which an example of 

 mimicry had been " thought to be useful, and to have been de- 

 signed as a means to a definite and intelligible purpose." He 

 accepts it as a product of natural selection, and since that time 

 it has been constantly used as a well-known example of this 

 principle, so well known, indeed, that the history of it became 

 unnecessary in any publication where space was an object. 



I neither originated the principle of aggressive mimicry nor 

 the VolucellcE as examples of it, although I accepted, and still 

 accept, both. Under these circumstances I must, in justice to 

 Kirby and Spence and A. R. Wallace, repudiate the discovery 

 of a significance I should have been proud to have made, but 

 which was made, as a matter of fact, about half a century before 

 I was born. It is only fair to these writers to say this, for Mr. 

 Bateson, although mentioning Kirby and Spence, seems 



