Oct. 24, 1889] 



NATURE 



619 



displacement occurring in the phylogeny of the Hydroids. 

 In the actual development these stages are repeated, and 

 the primitive germ-cells migrate from the ancestral to the 

 present position. From this it followed that the germ- 

 cells contained something sui generis : something that 

 could not be derived from the tissue-cells. 



The first and third essays, on the other hand, show how 

 a more or less theoretical consideration of death as a 

 factor in biology led to the establishing of an actual con- 

 tinuity of life from individual to individual in genealogical 

 series. In all animals above those consisting essentially 

 of a single cell, this continuity of life is confined to the 

 generative cells, and' it is the other, or somatic, cells alone 

 that are necessarily mortal. 



Such converging lines led to the provisional hypothesis 

 of a continuity of germ-plasma as the basis of heredity — 

 the hypothesis in fact, to take a simple instance, that it 

 is the eggs that have been forming the hens, and not the 

 hens the eggs, and so with their ancestors from the re- 

 motest of times. With this new view came the discussion 

 of the inheritance of acquired characters and the brilliant 

 interpretations and investigations of parthenogenesis and 

 polar bodies. Essay VII., on the supposed botanical 

 proofs of the transmission of acquired characters — which 

 has not before appeared in any form in English — and 

 Essay VIII., on the supposed transmission of mutila- 

 tions, are valuable contributions to the questions raised 

 by the general theory. 



There can be no doubt but that Dr. Weismann's essays 

 will be for long a source of inspiration and stimulus to 

 supporter and adversary, and this valuable translation 

 must prove of great service in making better known what, 

 if it never advances beyond the stage of a provisional 

 hypothesis, has already been of the utmost service to 

 biology. P. C. M. 



OUR BOOK SHELF. 



Chambers^ Encydopadia. New Edition. Vol. IV. 

 (London and Edinburgh : W. and R. Chambers, i88g.) 



In this volume of the new edition of " Chambers's Ency- 

 clopaedia," subjects from " Dionysius" to " Friction '"' are 

 dealt with. So far as we have been able to test it, we 

 have found that the volume is in no respect inferior to 

 its predecessors. The subjects include some that are of 

 great scientific interest and importance, and these have 

 been intrusted to writers whose names are a sufficient 

 guarantee for the character of their work. Prof. Tait 

 writes the article on force, Dr. W. Peddie those on 

 energy and ether, and Prof. Cargill G. Knott that on 

 electricity. Dynamos, the electric light, and the electric 

 railway are described by Prof. J. A. Ewing. The theory 

 of evolution is presented by Prof. Patrick Geddes, who, 

 while expounding his own doctrine, tries to give a per- 

 fectly fair account of the opinions of thinkers with whom 

 he only in part agrees. Dr. H. R. Mill has a good article 

 on the earth, and Prof. James Geikie discourses with his 

 usual clearness on Europe and on earthquakes. To 

 the article on France, Prince Kropotkin contributes the 

 geographical section. Prof. A. H. Keane is the author 

 of the article on ethnology ; and Dr. Henry Rink has a 

 short but interesting paper on the Eskimo. These and 

 other articles on scientific subjects in the present volume 

 cannot fail to maintain the high reputation of "Chambers's 

 Encyclopaedia " for accuracy and thoroughness. 



Farm Live Stock of Great Britain. By Robert Wallace, 

 Professor of Agriculture at the University of Edin- 

 burgh. Second Edition. (Edinburgh : Oliver and 

 Boyd. London : Simpkin, Marshall, and Co. 1889 ) 



This is a second edition of a work already reviewed in 

 Nature. The most important point of difference between 

 it and the first edition is the introduction of 100 excellent 

 plates, executed by Angerer and Goschl, of Vienna, from 

 photographs taken from life. Pictures are, no doubt, of 

 great assistance to a description, but, as the author justly 

 observes, photographs, although accurate, fail in some 

 respects to do justice to animals. This he attributes to 

 the awkward positions they assume while standing, and 

 the constancy of their motion while they remain on their 

 limbs. It is also, no doubt, partly due to the higher eleva- 

 tion of the eye of the observer than the camera as usually 

 employed. The levelness of the back and of the belly 

 lines is destroyed by the camera when placed horizontally 

 so as to strike the broadside of the animal. Prominences 

 are shown against the light, which in ordinary observation 

 do not disturb the levelness of the carcass. The work 

 has a strictly pastoral and agricultural interest. 



Days with Industrials j or, Adventieres and Experietices 

 among Curious Industries. By Alexander H. Japp, 

 LL.D. (London: Triibner and Co., 1889.) 



This book is a reprint, with additions, of a number of 

 articles which have appeared from time to time in various 

 periodicals of a popular character. The articles deal 

 with such subjects as quinine, rice, pearls, amber, common 

 salt, Burton ale and Dubhn stout, petroleum, canaries, 

 bedsteads, railway-whistles, knives, forks, and postage- 

 stamps — as heterogeneous a mixture, in fact, as the con- 

 tents of Mrs. Jellaby's famous cupboard. Dr. Jappv/rites 

 in a chatty and agreeable style, and his book may be 

 safely given to young people, with the certainty that they 

 will imbibe no false notions of science. 



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 op, rejected 

 manuscripts intended for this or any «t her part of Nature, 

 No notice is taken of anonymous communications.'^ 



Lamarck versus Weismann, 



I HAD not intended to reply to Mr. Cunningham's criticism 

 of a passage in my book which he thinks is pure Lamarckism 

 (see Nature, July 25, p. 297) ; but now that Prof. Ray Lan- 

 kester adopts the same view, I will make a few remarks upon 

 the case. Mr. Cunningham italicizes the words, " the constant 

 repetition of this effort causes the eye gradually to move round 

 the head till it comes to the upper side," and claims this as a 

 Lamarckian explanation. But if we italicize the following 

 words, which occur three lines further on, ^^ those usually sur- 

 viving luhose eyes retained more and more of the position into 

 which the young fish tried to twist them," we shall see that the 

 survival of favourable variations is, even here, the real cause at 

 work. For the transference of the eye to the upper side was a 

 useful change — perhaps, under the peculiar conditions of exist- 

 ence and development — an absolutely essential one. The amount 

 to which the eye could be twisted and retained in its new posi- 

 tion was variable, as all other such characters are variable. 

 Those individuals who had this faculty in the greatest degree 

 were among those that survived, and it is not at all necessary to 

 assume that any portion of the change due solely to the effort was 

 inherited, but only that those individuals which were the most 

 favourably constituted in this respect transmitted their peculiar 

 constitution to their offspring, and thus the twisting would take 

 place earlier and earlier in the development of the individual 

 Even Darwin himself, who believed in the heredity of acquired 

 variations, says that "the tendency to distortion would no doubt 

 be increased through the principle of inheritance " ; and this is 

 really all that is necessary. In most of the higher animals sym- 



