486 



NATURE 



[March 21, 1889 



only terminate with the life of the unfortunate subject. This 

 power of growing afresh so complex and specialized an organ as 

 an eye is certainly at first sight not a little astonishing, but it 

 appears to be capable of a very simple explanation : the cells 

 terminating the cut stump of the tentacle are the ancestors of 

 those which were removed ; a fresh series of descendants are 

 derived from them, similarly related to the ancestral cells as 

 their predecessors which they replace ; the first generation of 

 descendants become in turn ancestors to a second generation, 

 similarly related to them as were the second tier of extirpated 

 cells ; and this process of descent being repeated, the completed 

 organ will at length be rebuilt. The possibility of this arises 

 from the fact that in the snail the embryological course of 

 development is capable of being repeated by the adult structure. 

 In higher organisms this possibility does not as a rule exist, and 

 mutilation is not followed by regeneration ; but even in their 

 case the ancestral cells remain, and when the embryological 

 development is repeated their representatives in the embryo are 

 present to give rise to descendants of the normal type in the 

 normal fashion. It follows from this view, which leaves pan- 

 genesis out of account, that mutilations cannot possibly be in- 

 herited, and this for the reason that the cells forming the 

 organism at each stage of its development must be regarded as 

 the ancestors of those of the next stage; thus finally we are 

 brought round to something which looks very like Weismannism. 



W. J. SOLLAS. 



Trinity College, Dublin, March 15. 



P.S.— The foregoing completely accounts for the non-inherit- 

 ance so often referred to of the character produced by circum- 

 cision. In the case of a snail it might be presumed that 

 circumcision could not produce any persistent result ; in the 

 human subject what is remarkable is not the reappearance of the 

 prepuce in the descendant, but that no regrowth beyond healing 

 takes place in the subject. 



Mr. Marcus M. Hartog's letter of March 6 inserted in last 

 week's number (p. 462), is a very valuable contribution to the 

 growing evidence that acquired characters may be inherited. I 

 have long held the view that such is often the case, and that I 

 have myself observed several instances of the, at least I may say, 

 apparent fact. 



Many years ago there was a very fine male of the Capra 

 megaceros in the gardens of the Zoological Society. To restrain this 

 animal from jumping over the fence of the inclosure in which he 

 was confined, a long and heavy chain was attached to a collar 

 round his neck. He was constantly in the habit of taking this 

 chain up by his horns and moving it from one side to another 

 over his back ; in doing this he threw his head very much back, 

 his horns being placed in a line with the back : the habit had 

 become quite chronic with him, and was very tiresome to look at. 

 I was very much astonished to observe that his offspring inherited 

 the habit ; and although it was not necessary to attach a chain to 

 their necks, I have often seen a young male throwing his horns 

 over his back and shifting from side to side an imaginary chain. 

 The action was exactly the same as that of his ancestor. The 

 case of the kid of this goat appears to me to be parallel to that 

 of child and parent given by Mr, Hartog. I think at the time I 

 made this observation I informed the late Mr. Darwin of the fact 

 by letter, and he did not accuse me of "flat Lamarckism." 



J. Jenner-Weir. 



Chirbury, Beckenham, Kent, March 16. 



where IT satisfies the equation — 



v-n = A--" 



The corresponding Maxwellian equations would be — 



dh _ dZ _dY dM ^dX _ dZ dN ^dV _ dX 



di dy dz dt dz dx ' dt dz ' dy ' 



.^dX dm. rfN „ 

 A^ = - - . , &c., 

 dt dz dy 



with the solutions, X, Y, Z, as before, and 



.d-'n 



, IVI = — /\ - 



dydt 



The more general solutions of the field equations would be- 

 d 



A2'r " N 

 dzdt 



V 'i '^ 

 ^=dy\^ix-'^ 



.J)-|(' 



dx ^d> 



L = A 



.df d 

 d\ dy 



"i- 



Hertz's Equations in the Field of a Rectilinear Vibrator. 



In Dr. Oliver Lodge's valuable communication to Natxjre 

 of the 2ist ull. (p. 402), giving Hertz's equations for the field of 

 a rectilinear vibrator, may I suggest the following very slight 

 change, in order to bring the formulae into complete accord 

 with those of the Maxwellian theory. 



Hertz has, with A^ = juK, 



L = A ^\ M = - A '^^", N 

 dyut dzdt 



with corresponding expressions, mutatis fnutandis, for Y, Z, 

 M, N ; where A, jx, v, are arbitrary constants, coinciding with 

 Hertz's results when X = o, fj. = o, v = - i. 



H. W. Watson. 



Alternative Path Leyden Jar Experiments. 



In your issue of Feb. 14 (p. 380) there is an " Electrical Note " 

 which is very misleading. You will perhaps allow me to say, 

 therefore, that Mr. Acheson's photographs show no evidence of 

 oscillation whatever ; that his experiments are aimed at practical 

 questions connected with lightning protectors, and confessedly 

 were not made in such a way as to have any theoretical im- 

 portance ; that in so far as Mr. Acheson thinks he is expounding 

 a new theory by calling self-induction " extra currents " he is, 

 in my opinion, mistaken ; and finally, that the author of the 

 note, in speaking about " the errors due to charging which 

 vitiated Prof. Lodge's early experiments," is talking about 

 I something which has no existence. Oliver J. Lodge. 



The Celluloid Slide-Rule. 



Celluloid has been applied to so many purposes, that one 

 is never surprised to see one or other of its many valuable pro- 

 perties turned to account in some new way. A slide-rule is now 

 made, in which the surfaces on which the divisions are engraved 

 consist of thin sheets or veneers of dead white celluloid. The 

 diyisions are beautifully sharp and distinct. If these veneers do 

 not come unfastened, and the rule does not lose its dead white 

 surface with use and exposure, this new application of celluloid will 

 be found a most valuable one. The rule examined is one almost 

 identical in pattern with the well-known Gravet instrument, and, 

 if one ir.ay judge by the scale, the accuracy of the divisions, and 

 the smoothness of the motions, it is made by the same machinery. 

 The differences are mere differences of detail. Mahogany takes 

 the place of boxwood The cursor runs on an improved form 

 of slide. Chisel-edges, instead of cross-lines, on the cursor are 

 used to transfer readings. There is only one opening at the 

 back, so tangents cannot be read without reversing the slide. 

 The millimetre scales at the two edges are replaced by scales 

 of inches. It is a pity that one of the scales of millimetres has 

 not been left. The agents are John Davis and Son, of Derby 

 and 118 Newgate Street, and the price is rather less than that at 

 which the ordinary Gravet can be obtained in this country. 



C. V. Boys. 



The Philosophical Transactions. 



Your correspondent " S." seems to be unaware that what he 

 asks for has been already done. The abridgment of the Philo- 

 sophical Transactions, which was brought down to the year 

 1800 by Charles Hutton, George Shaw, and Richard Pearson, 

 was continued in octavo form, by order of the President and 

 Council of the Koyal Society, under the title of "Abstracts of 

 the Papers printed in the Philosophical Transactions of the 

 Royal Society of London." This series extended to six volumes, 

 bringing the abridgment down to the year 1854. At the seventh 

 volume the title was changed to "Proceedings of the Royal 

 Society of London," a publication which still exists, and which 

 contains abstracts of all the papers in the Philosophical 

 Transactions and a good deal besides. H. R. 



