126 



NA TURE 



[June io, 1897 



genera and species. In a work with such a title one 

 expects rather to find a detailed description of the 

 methods of procedure as regards capture, habits, habi- 

 tats, &c., and not to require the young collector to plunge 

 itt inedias res without such knowledge. The introduction 

 certainly attempts to deal with these points, but it only 

 consists of eleven pages of large print ; and the all- 

 important subject, in such a work, of "the habits of 

 beetles and how to catch them " is dismissed in about 

 thirty lines. 



The plates are worth the cost of the work, which may 

 be found useful for a somewhat more advanced student, 

 but which hardly appears to realise our idea of a "Young 

 Collector's Handbook." 



Exercises in Practical Physiology. By Augustus D. 



Waller, M.D., F.R.S. Part iii. Pp. 91. (London : 



Longmans, Green, and Co., 1897.) 

 The exercises and demonstrations contained in this and 

 the two preceding parts are primarily intended to facili- 

 tate class work in physiology, and for use in conjunction 

 with such a text-book as the author's " Introduction to 

 Human Physiology." The present part contains sixty- 

 eight instructive experiments on the physiology of the 

 nervous system, and descriptions of the instruments used 

 in investigations in electro-physiology generally. The 

 subject is one which the author has made peculiarly his 

 own ; so that the experimental details will be found 

 sufficient to enable students and demonstrators to set 

 up the required apparatus satisfactorily and obtain good 

 results. The book affords a strong argument for the 

 teaching of the principles of physics to students of 

 physiology ; for without this fundamental knowledge 

 it would be impossible to perform the experiments 

 intelligently. 



Year-Book of the Scientific and Learned Societies of 



Great Britain and Ireland. Fourteenth annual issue. 



Pp. 270. (London : Charles Griffin and Co., Ltd., 



1897.) 



This work, in addition to being a convenient handbook 



of our scientific societies, contains lists of the papers 



read during 1896 before societies engaged in fourteen 



departments of research. It is thus a very useful index 



to scientific progress, as well as an indispensable book of 



reference to the officers, places and times of meetings, 



publications, and membership fees, of British Societies 



for the advancement of knowledge of every kind. 



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 

 inamiscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. '\ 



The Trotting Horse. 



In "The Primary Factors of Organic Evolution," Prof. Cope, 

 whose recent death has taken from us an untiring worker and 

 suggestive writer, adduces the evolution of the trotting horse as 

 an illustrative case of the inheritance of characters due to the 

 exercise of function (p. 426). Prof. Brewer, of Yale, is quoted 

 at some length. He says : " There is every appearance and in- 

 dication that the changes acquired by individuals through the 

 exercise of function have been to some degree transmitted, and 

 have been cumulative, and that this has been one factor in 

 the evolution of speed. . . . There is nothing whatever in the 

 actual phenomena observed anywhere along the line of this 

 development of speed that would lead us to even suspect that 

 the changes due to exercise of function had not been a factor in 

 the evolution, and there is not a particle of evidence, other than 

 metaphysical deductions, much less proof, that it would or could 

 have gone on just the same by mere selection and adventitious 

 variation" (pp. 429-430). 



Mr. A. J. Meston, of Pittsfield, Mass., has recently discussed 

 this question statistically in a pamphlet entitled " The Common 

 Sources of 2"io trotting and pacing speed." The results of this 

 seemingly very careful investigation are of such general biological 

 interest, that I have no hesitation in requesting space to draw 

 attention to Mr. Meston's conclusions. 



The first point that is especially noteworthy is the predominant 

 influence of one horse, Hambletonian 10(1849-1870). "While 

 we have extreme speed without the aid of Hambletonian, it is, 

 nevertheless, a fact that the influence of Hambletonian has been 

 exerted amongst 92 per cent, of the 2" 10 trotters, and 84 per 

 cent of the 2* 10 pacers [that is to say, trotters or pacers who 

 can cover a mile in two minutes and ten seconds or under] We 

 have pacing speed, apart from Hambletonian, within two seconds 

 of the best record ; but trotting speed without Hambletonian is 

 four seconds behind the fastest mile. No mile has yet been 

 trotted faster than 2-07! without the aid of Hambletonian. . . . 

 Furthermore, the majority of both the trotters and pacers that 

 descend from Hambletonian have more than one cross of his 

 blood. ... A very superficial examination of the blood of 

 the 2'io list shows that Hambletonian has exerted a predominant 

 influence in its formation " (pp. 6-7). 



The second point is the conclusion to which Mr. Meston is 

 led with regard to the transmission of acquired speed. " It 

 appears from the table," he says, "that some stallions and 

 mares, after having been trained to fast records, have got foals 

 that made fast records. It also appears that demonstrated 

 capacity for speed and the ability to beget speed are qualities 

 possessed in common by many stallions and mares, but the 

 relative dates of ' making the record ' and ' getting the foal ' 

 exclude the affirmation, if not the probability, of cause and effect 

 between the two occurrences. It does not appear that a line of 

 trained ancestors is more successful in producing speed than a 

 line of untrained ancestors, or a mixed line of trained and 

 untrained ancestry. Therefore, the evidence is negative upon the 

 question whether increase of speed acquired by the individual 

 through training, habit, or experience, is passed on to the foal, 

 in any degree, by the force of heredity. On the other hand, the 

 evidence is positive and convincing that congenital capacity for 

 speed and innate plasticity for the development of speed are 

 transmitted hereditarily to progeny, and that, by judicious or 

 fortunate crossing, the capacity and plasticity have been vastly 

 increased " (p. 23). 



As this is the most careful statistical investigation of the kind 

 with which I am acquainted, it appears to me that Mr. Meston's 

 conclusions (which, he informs me, were not those that he 

 anticipated at the outset of his inquiry) are worthy of careful 

 consideration. C. Lloyd Morgan. 



Bristol. 



Fire-fly Light, 



In Wiedemann's Atmaleu for December last. Prof. H. 

 Muraoka published an account of the rays which he found to be 

 emitted by a fire-fly (described by him as a " Johanniskafer '), 

 and which resemble the rays which Dr. Dawson Turner has 

 found to be emitted by glow-worms, in that they can pass (like 

 Rontgen's rays and uranium rays) through aluminium. Can any 

 reader of Nature state what species of insect is known by this 

 name? Muraoka describes thein as on the average 13-15 mm. 

 long ; the largest being 20 mm. long. He says they have two 

 (or in smaller insects three) rows of luminous spherules on the 

 under side of its body, but that the whole body is photo- 

 graphically active. He used about 1000 insects at a time, with 

 exposures of two to three days. 



June 6. SiLVANUs P. Thompson. 



THE LIQUEFACTION OF FLUORINE.^ 



"T^HE physical properties of a large number of inineral 



-*- and organic fluorine compounds led to the theoretical 



prediction that the liquefaction of fluorine could only be 



accomplished at a very low temperature. 



Whilst the chlorides of boron and silicon are liquids 

 at the ordinary temperature, the fluorides are gaseous, 

 and well removed from their boiling points. The same 

 difference is noticeable in their organic compounds, 



1 " On the Liquefaction of Fluorine," by H. Moissan and J. Dewar. 

 (Translated from Comptes rendus of the Paris Academy of Sciences, May 31, 



NO. I44I. VO L. 56] 



