;i6 



X.-4 TURE 



[August i, 1895 



Ltiboratory Exercises in Botany. By Prof. Edson S. 



Bastin, A.M. (Philadelphia : W. B.' Saunders, 1S95.) 

 For a laborator>- manual this book is of i,'reat extent, for 

 it includes more than 500 octavo pages, with no less than 

 87 plates. Yet it is more remarkable for what is omitted 

 than for what is contained in it. 



The first half of the book is devoted to organography, 

 and consists of descriptions of the gross structure of a 

 number of types of flowering plants, fully illustrated in 

 the first 37 plates. This part of the book seems to us 

 decidedly well done. 



The second half, with 50 plates, is on vegetable 

 histology. Strange to say, it deals simply and solely 

 with the vt-gclaiivc structure of phanerogams and \ ascular 

 cryptogams. This branch of the subject is illustrated in 

 great detail, and the anatomical work is sound, if not 

 quite up to the highest modem standard. 



Not a word, however, is said as to reproduction,- 

 development, or life-histor)-. The words polkn-ttihc, 

 tn'tile, cDibryo-siU, arcliegonium, anthcridiuiit, and grinu- 

 ing-point, are sought in \ain in the index, nor ha\e we 

 found any reference to them in the text, except that 

 ovules are of course mentioned in the descriptive part. 

 In fact, just those subjects which are most important in 

 a scientific course of laboratory work are entirely passed 

 over. The utter absence of any account of the lower 

 cryptogams is also astonishing, for there is no indication 

 that a second volume may be looked for. 



The author is professor at a pharmaceutical college, 

 and this fact may help to account for the extraordinary- 

 unevenness with which he has treated his subject. 

 .Students of pharmacy in .America arc no doubt required 

 to have some acquaintance with the external characters 

 of the higher plants, and some anatomical training may 

 also be expected of them, with a view to the identification 

 of drugs. Beyond this it would ai)pear that their botanical 

 education is not meant to go. The author has expended 

 great pains on his work, but its manifest one-sidedness 

 renders it quite valueless as a scientific guide to labor- 

 atory botany. Students of phaniiacy in England are 

 happily accustomed to a very dilTercnt system of botanical 

 teaching. D. H. S. 



The Source and Mode of Solar Eiwrify. My I. \\. I 

 Heysinger, M..\., M.D. (Philadelphia*:' J. B. Lippin- | 

 cott and Co., 1895.) 

 On the strength of an acquaintance with popular astro- 

 nomical literature, in many cases not up to date, the 

 author of this work offers a theory which he stales to be 

 capable of interpreting all the phenomena presented to 

 us in the heavens. Briefly, we are asked to believe that 

 all interstellar space is filled with attenuated water 

 va|>our, and that this vapour is decomposed into its con- 

 stituents by the electricity generated by the movements 

 of planetary bodies ; the oxygen remains on the planets, 

 while the hydrogen goes to maintain the incandescence 

 of the central suns. The author deals very ingeniously 

 with many of the apparent difficulties, such, .for ex- 

 ample, as the absence of an atmosphere from the 

 moon ; but his anxiety to leave nothing unexplained, has 

 onally demanded other assumption', and led to 

 ntradictions. Thus, in regard to comets, it is 

 ..I- .^TTiry to suppHJSc, from the repulsion of the tails, that 

 when they enter our systein, they do not behave electri- 

 ralK .1^ r.Iinets do, but like suns, and so they should 

 li ' -:in atmospheres ; on the other hand, since 



'1 '.-.umed to be a "planetary" clement (p. 69), 



they should not contain carbon. This is in complete 

 contradiction with the facts. The author is so much 

 behind ihi- Inn'-', in spectroscopic matters as to imagine 

 that nebul.i abdiind in free nitrogen, and possibly oxygen, 

 and that free nitrogen and hydrogen are characteristic of 

 comets. It »vould serve no good purpose to discuss a 

 thcor\' based on such misconceptions. 



NO. 1344, VOL. 52] 



LETTERS TO THE EDITOR. 



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

 pressed 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 Huxley Memorial. 



I TRUST you will allow me through the medium of your 

 columns to make it known that at the meeting of the Provision.-U 

 Commitlee, which was helil at the rooms of the Royal SiKiety 

 on Tuesday afternoon, it was amiouncod that a large number of 

 acceptances had already liten received to the invitation which 

 was issued a few days ago to a number of gentlemen to serve on 

 the General Committee which it h.ad been decided to form to 

 inaugtirate a National Memorial to the late Right Hon. T. H. 

 Huxley, F.K.S. 



.■\ list of the Committee will shortly be published. 



Owing to the lateness of the sea.son, it has been decided to 

 defer until after the autumn recess the meeting of the tlenera! 

 Committee, at which the propos,ils of the Provisional Co;nmittee 

 with regard to the form which the National Memorial shall take 

 may be discussed and decided. 



With a view of a.ssisting the Pro\-isional Committee in arriving 

 at .some general ideas on the subject, it is suggested that those 

 who projwse to contribute to the fund might be willing to inform 

 the Trea.surer of the probable amount of their subscriptions. 



Subscriptions will be received and aeknowledgeil by adverlise- 

 ment in The Times by the Treasurer, Sir John Lubbock. 



J. D. Hooker, 



July 30. Chairman of the Provisional Committee. 



The Kinetic Theory of Gases. 



Wic shall all agree with Dr. Boltzmann's views as ex]iressecl 

 in Nati'kk of July 4, that if in a system of elastic sphere 

 molecules the free paths be very long, anil if at the s;ime lime 

 the system be of unlimited extent, condition .A will always be 

 satisfied. The system will go on till it attains Nirvana in the 

 Maxwell-Boltzmann distribution. 



It is <inly for a finite system that it api)eared to me that 

 occasional disturbances from the outside were necessary to pro- 

 duce this result. I agree with Mr. liryan that contact with the 

 refrigerator or with the reservoir, such as is supposeil to take 

 l)lace in thermodynamics, is for this purpo.se a disturbance. 



But it is this very length of free path, and condition \ 

 which follows from it, that restricts our kinetic theory to the 

 limiting case of a rare gas. 



We have, as I maintain, to abandon condition .\ altogether if 

 we wish to present our theory in a form applicable to ilense 

 media. We must consider, not single spheres, but groups of 

 spheres to begin with. Civen that there are at this instant it 

 spheres, and no more within a spherical sjKice S, but nothing is 

 known of their position within .S, what is the chance that their 

 component velocities shall at this instant be 



«, . . . Ui + dUi re,, . . . -Wn + dlCnf 



I a.ssume that chance to he 



Cf^idui . . . du;„ 



in which (> = ai{u' + t" + tf') + fiSi{uu' + ti/ + jom'), the 

 summation including the n spheres and ever)' [lair of them. The 

 coefticienl /' excludes condition .\. 



Hut whatever be the v.ilues of ,1 and b, this distribution of 

 velocities remains undisturbed by collisions. .\nd by suitably 

 choosing ii and /', we can satisfy all other necessjiry conditions. 



The same thing can lie done for two sets of spheres of une(|ual 

 ma-sses in and «;'. In that case we must put t,) in the form 



n = ri2(i/' + if + w') + a'i(u"' + v'^ + tti'') 



t bii(ii'fU, + VfV, + WfU',) + h'XSiu'fii'^ + f'pv',, + w'f-w'.,) 

 + $H{uu' + ird + vtv'), 



in which the accents ' refer to the ///' set, Jiml iSu/i't, <.V<.» 

 means sunnnalion over all pairs of spheres in, iVc. 



Here we have five coeflicienls, a, b, d, b', $. But the condi- 

 tion for permanence, notwithstanding collisions between 111 and 

 ;/;', recpnrcs 



2(1///' - 2a'm + P[iii' - ///) = o 



b = '"B b'^"''0. 

 m /// 



1 



