NA TURE 



[November 30, 1905 



is little more than a fixed fleshy stalk, upon which 

 grows the body and its shell " — " a palpable case of 

 what we call degeneration." If all degeneration were 

 on the lines of the barnacle's life-history, it would be 

 difficult to distinguish it from progress. We wish 

 there had not been these and other blemishes in this 

 sprightly and interesting little book, for it is sure to 

 be popular. J. A. T. 



Lc Chauffage des Habitations par Caloriferes. By 

 M. Raymond PeYisse. Pp. 173. (Paris : Gauthier- 

 Villars et Fils, n.d.) Price 2A francs. 

 This little work is of a very practical nature; and 

 although it appeals more particularly to the engineer 

 and architect it may be read with advantage by the 

 general reader, for it sets out, in a manner which is 

 clear and easily intelligible to all, the advantages 

 which accrue from the systems of heating dwellings 

 by the various warming apparatus which are in- 

 stalled, not in the living rooms, but on the ground 

 floor or in the basement. The advantages in the 

 use of steam, hot-water, or hot-air apparatus, instead 

 of fireplaces or stoves, are certainly real ones ; for 

 the house is more uniformly and better heated, at a 

 less expense, trouble, and risk, and the apartments 

 are not encumbered with the large stoves so generally 

 seen on the Continent. 



The advantages and disadvantages of the different 

 systems are explained, and various applications of 

 these systems are illustrated. The reader is also told 

 how each may be best applied and regulated to meet 

 the variable requirements as to heat, the different 

 circumstances of the dwelling, the conditions of 

 occupancy, and the like. 



Auslese aus meiner Unterrichts- und Vorlesungs- 

 praxis. By Dr. Hermann Schubert. Erster Band. 

 Pp. 240. (Leipzig: G. J. Goschen, 1905.) Price 



4 marks. 



Ten chapters dealing with a variety of subjects — 

 logarithms, cyclotomy, the theory of physical dimen- 

 sions, systems of circles and spheres being the most 

 important. The principal novelty is the treatment of 

 logarithms (pp. 1-68), fair approximations being 

 obtained by combining inequalities such as 



— log m + 2 log (m+i) — log (m + 2)>o. 



The method is quite elementary and very ingenious, 

 but it has no practical value, and strikes one as being 

 artificial. The chapter on dimensions (reprinted from 

 the Natunv. Wochenschr., 1895) is interesting, but 

 not convincing ; its essential feature is 



[mass] = [length] 3 [time]- 2 . 



Pangiomitrie ; on Precis de Giomitrie fondSe sur 

 une Theorie gdnirale et rigoureuse des Par alleles. 

 By N. J. Lobatschewsky. Reimpression facsimile 

 conforme a l'edition originale. Pp. 279-340, and list 

 of errata. (Paris : A. Hermann, 1905.) Price 



5 francs. 



Lobatschewsky shares with the Bolyais the credit of 

 founding the theory of non-Euclidean geometry, in 

 which Euclid's axiom of parallels is not assumed to 

 be true. His " Pangeometrie " was communicated 

 to the mathematical faculty of the University of 

 Kazan in 1855 on the occasion of his jubilee ; this 

 fact might well have been indicated in the present 

 reprint. It is the author's last and most complete 

 exposition of his theory, and mathematicians will be 

 glad to have it in this accessible form, though, like 

 other similar reprints, it is rather trving to the eye- 

 sight. 



NO. 1883, VOL. J^] 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

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

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



The Bates-Muller Hypothesis of Mimicry : a Question 

 of Historical Accuracy. 



A paper dealing with the above subject, by the late Dr. A. 

 S. Packard, has just been published in the Proceedings of 

 the American Philosophical Society (vol. xliii., No. 178, 

 p. 303), in which this well known entomologist endeavours 

 to show that the markings of organisms (" pcecilogenesis ") 

 are " due to the physical rather than to the biological 

 environment." I must leave it to others to consider how 

 far the late author has established his case as against 

 Bates, Fritz Midler, and those who have accepted the 

 theories of mimicry associated with these names. My 

 object in asking you to give space to this letter is to 

 point out a distinct error which, if allowed to pass un- 

 challenged, is likely to be accepted as a true statement of 

 Darwin's views in the sense conveyed by the American 

 writer. 



Happening to know the actual history of the Miillerian 

 theory of mimicry through the courtesy of Mr. Darwin 

 himself, I can assure those who read the paper that the 

 passage which is quoted does not refer to that theory 

 at all. In the letter to Fritz Midler referred to (August 

 28, 1870) Mr. Darwin says : — " I should not be at all 

 surprised if your suggestion about sexual selection were 

 to prove true ; but it seems rather too speculative to be 

 introduced m my book," &C (" More Letters," vol. ii., 

 p. qi). Now Dr. Packard quotes only the words which I 

 have italicised as " Darwin's own estimate of Midler's 

 little paper," but this is a misstatement of the facts. 

 Darwin, it will be observed, is referring to a suggestion 

 about sexual selection, and I am in a position to state 

 what that suggestion was. At the date of the corre- 

 spondence quoted (1870), Fritz Midler had observed the 

 striking resemblances, or "mimicry," between butterflies 

 belonging to " protected " groups, as, in fact, Bates had 

 done before him. In searching for an explanation of this 

 apparent violation of the Batesian theory, he suggested 

 that it almost appeared as though the females of one pro- 

 tected species had been influenced in their choice by si • ■ i 11^. 

 the predominant pattern of other protected species always 

 about them. Mr. Darwin was good enough to allow me 

 to read Midler's letter to him, and in forwarding it to me 

 in 1872 he added : — " You will also see in this letter a 

 strange speculation, which I should not dare to publish, 

 about the appreciation of certain colours being developed 

 in those species which frequently behold other forms 

 similarly ornamented " (" Charles Darwin," by E. B. 

 Poulton, p. 202). This is the " suggestion about sexual 

 selection " to which Darwin refers in his letter to Midler, 

 and, so far as my memory serves me, I do not think this 

 speculation was ever formally published to the scientific 

 world. 



The Mullerian theory which the late Dr. Packard con- 

 sidered that he had demolished was not published until 

 1879, the " little paper " in question having been con- 

 tained in a number of Kosmos which Mr. Darwin 

 forwarded to me in that year. On reading the said note 

 I was at once convinced that Midler had found the true 

 explanation of mimicry between protected groups, and 

 I accordingly directed Mr. Darwin's attention to the 

 matter and published a translation of the paper (Proc. 

 Ent. Soc, 1879, p. 20) in order to bring it under the notice 

 of English entomologists. Writing to me in 1879 about 

 this paper, Mr. Darwin said : — " F. Muller's view of the 

 mutual protection was quite new to me " (Poulton, loc. 

 cit., p. 213). It is thus evident that Dr. Packard 

 confused a tentative speculation of Midler's, which was 

 contained only in a letter to Darwin, and probably never 

 intended for publication, with the now well known 

 Miillerian theory which was published formally some nine 

 years later. 



R. Meldola. 



