Nov. 13, 1884] 



X.I TURE 



27 



as the period of the solar semi-diurnal tide, and that the 

 solar tide might undergo such kinetic augmentation as to 

 rupture the planet. A piece torn off might form the 

 moon. The suggestion was only thrown out tentatively, 

 and it might perhaps have been better had it been sup- 

 pressed. The whole essence of the suggestion lies, how- 

 ever, in tin' approximate identity of the free and forced 

 periods of oscillation, and this reasoning has no place in 

 Spiller's theory. 



In considering the history of a cooling planet, the author 

 is opposed to Sir William Thomson, and concludes 

 that the surface would harden into a crust. It seems to 

 me that the time is hardly ripe for a very confident opinion 

 on the point. 



A large place is given in this book to the influence of 

 tides in the evolution of a planet. A description is given 

 of the tidal retardation of planetary rotation and the 

 recession of the satellite ; and the chapter is in fact prin- 

 cipally a resume of my own papers. The author is at one 

 with me in rejecting Prof. Ball's view, that an enormous 

 exaggeration of marine tides can have taken place within 

 geological history. He is inclined to adopt the view that 

 the trends have been imparted to our great continents by- 

 means of the wrinkling consequent on tidal friction in a 

 primitively viscous mass ; but he hardly notes, as I pointed 

 out, that if this be so we have to accept a continuous 

 adjustment of the general ellipticity of the earth to a figure 

 of equilibrium, without obliteration of the wrinkles. The 

 suggestion is thus perhaps placed in almost too favourable 

 a light. 



On p. 282 Mr. Winchell speaks as though solar tidal 

 friction is adequate to cause a sensible lengthening of the 

 year, so that in earlier ages it was sensibly shorter. It is 

 impossible to admit the correctness of this view, as I have 

 elsewhere shown. 1 



In a section on orogenic forces we have, amongst much 

 other interesting matter, an account of M. Favre's experi- 

 ment, in which a layer of clay is placed on a tense elastic 

 membrane, which is then allowed to contract : an illustra- 

 tion of many of the facts of mountain geology is thus 

 furnished. 



In the following chapter the author follows the various 

 lines of argument by which limits are placed on the age 

 of a planet, and by a subsequent geological discussion 

 endeavours to derive a time scale ; but I feel incompetent 

 to judge of the worth of the conclusion. We may regret 

 to find the revival in this place of Prof. Haughton's argu- 

 ment, viz. that the absence of a measurable nutation of 

 306 days proves the enormous antiquity of the elevation 

 of Europe and Asia. The argument is, I think, worthless, 

 as I believe that Prof. Haughton now admits. 2 



The principal topics dealt with in the rest of the book 

 are the geology of the moon, the physical condition and 

 habitability of other planets, and the final effects of tidal 

 friction. 



The fourth main division of the book is historical, and 

 contains a review of the evolution of cosmogonic theories, 

 with an exposition of the speculations of Kepler, Descartes, 



■ Phil. Trans. Part 2, 1881, p. 524 : " From this ic f.,11, iws that, if the whole 

 of the momentum of Jupiter and his satellites were destroyed by solar tidal 

 friction, the mean distance of Jupiter from the sun would only be increased 

 by 1 25000th (misprinted 1, 2500th) part. The effect of the "destruction of 

 the internal momentum of any other system would he very much less." 



- &e I'm. /.' .V. February 19, 1878, No. 186, p. t, "On Prof. Haughton 's 

 Estimate of Geological Time." 



Leibnitz, Swedenborg, Kant, Lambert, William Herschel, 

 and Laplace. 



From the account which has now been given of this 

 work it must be evident that Mr. Winchell set before 

 himself a task of portentous magnitude, and that he has 

 performed it conscientiously. The criticisms which have 

 been made should not impair the conviction that the 

 student of this group of subjects will find his work of 

 great value. G. H. Darwin 



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. 

 No notice is taken of anonymous communications . 



[ The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible otherwise to insure the appearance even 

 of communications containing interesting and novel facts. ] 



The Pentacrinoid Stage of Antedon rosaceus 

 In compliance with Prof. Herdman's request, I have to state 

 that my experience — acquired during seven years of consecutive 

 dredging in Lamlash Bay (1S55-61) — is in entire accordance 

 with his own. Although the most active period of reproduction 

 in Antedon rosaceus is undoubtedly (as stated by Sir Wyville 

 Thomson) the .ir.Ypart of thesummer, so that the Pentacrinoids 

 which spring from the ova then matured and fertilised are ready 

 to drop off their stems in the succeeding autumn, yet I never 

 failed to obtain Pentacrinoidi in all stages, as well as Antedons 

 still "in fruit," throughout the months of August and Septem- 

 ber. In fact, the whole of my study of this type — which, as 

 regards the skeleton, is fully recorded in my memoir in the 

 Philosophical Transactions for 1S65, and of which, as regards 

 the soft parts, a general account is given in the Proceedings of 

 the Royal Society for 1S76, was carried out during those 

 months ; my official duties keeping me in London until after the 

 first week in August. 



I may take this opportunity of directing the attention of those 

 interested in Crinoidal structure (i) to a communication I have 

 recently made to the Royal Society {Proceedings, May 29) on 

 the Nervous System of the Crinoids ; (2) to a paper by Prof. A. 

 Milnes Marshall in the Quarterly Journal of Microscopical 

 Science for July last ; and (3) to a paper by Dr. Carl Jickeli of 

 Jena, in the ZojI Aoz-iger, 7 Jahrgang, No. 170. — The doctrine 

 I propounded on this subject nearly twenty years ago (that the 

 quinquelocular organ contained in the centro-dorsal basin of 

 Antedon is a nerve-centre, and that the radial cords issuing from 

 it, which traverse the calcareous segments of the arms and pin- 

 nules, and give off branches to the successive pairs of muscles, 

 are nerve-trunks), though supported by the experimental evidence 

 which I published in 1876, and by the careful microscopic inves- 

 tigations of my son, Dr. P. Herbert Carpenter, has not been 

 accepted by Zoologists generally ; being for the most part either 

 ignored altogether, or pooh-poohed as "evidently" fallacious, 

 because inconsistent with homol igical theory. When I made 

 my recent communication (1) to the Royal Society, summing 

 up the very remarkable confirmatory evidence afforded by 

 my son's inquiries, and referring (as Prof. Marshall had 

 kindly enabled me to do) to the then unpublished results 

 of his experiments (2), which entirely tallied with my own, Prof. 

 Huxley, while admitting the strength of my case, remarked 

 that the position I assign to the nervous system of the Crinoidea 

 is as anomalous (in relation to that of Echinoderms generally) as 

 it would be for a Vertebrate animal to have its spinal cord lying 

 along its ventral surface. In reply, I asked, " What more proof 

 can you ask for, of the nervous function of the quinquelocular 

 organ and radial cords?" The only additional evidence that 

 Prof. Huxley could suggest, was the result of electric stimulation. 

 Before my paper was published in the Proceedings, I learnt (3) 

 that this experiment had been actually tried four years ago by 

 Dr. Jickeli, whose results entirely confirmed my doctrine. 



It is to be hoped, therefore, that those who have so confidently 

 and persistently clung to a homology, which is in direct contra- 

 diction to the most complete and conclusive proof that experi- 

 ment can afford — supported as this is by the large body o 



