August 4, 192 1] 



NATURE 



715 



there set forth that it may seem ungrateful of me to 

 venture to reply to anything the reviewer has written. 

 Nevertheless, there is one important point in which 

 I feel that my argument has been missed. My con- 

 ceptions of the relation between recapitulatory and 

 mutational characters are not easy to state clearly in 

 a brief space, and I am willing to admit obscurity in 

 certain passages, as evidenced by your reviewer's 

 failure to grasp my meaning, but I am not willing 

 to plead guilty to the more serious charge of 

 obscurantism. 



The argument was not that mutations are limited 

 in their scope by the existence of non-cellular struc- 

 tures in organisms, but rather that embryonic char- 

 acters which show recapitulation, and at the same 

 time imply re -adaptation of the organism, cannot have 

 arisen by chance mutations in the germ-plasm, but 

 must have arisen as environmentally induced responses 

 which could become germinal only according to the 

 principle of the inheritance of acquired characters. 



By general agreement mutations arise as such in 

 the germ-plasm, i.e. probably in the chromosomes. 

 But there is another possible route into the germ- 

 plasm, namely, via a modified soma (probably in its 

 beginning a modified cytoplasm), ultimately affecting 

 the germ-nuclei. 



Orthogenetic changes I placed in a third category 

 as showing recapitulation and yet arising in the germ'- 

 plasm, since they are non-adaptational, and hence 

 probably not environmentally impressed on the 

 organism. The relations between these three types of 

 characters are admittedly obscure, but it does not 

 follow that they are non-existent or that the con- 

 ceptions regarding them are obscurantist. I wished 

 particularly to contrast mutations and embryonic re- 

 capitulatorv characters from the point of view of 

 organic structure, indicating that the principles which 

 will explain the one cannot adequately explain the 

 other, R- RuGGLEs G.\tes. 



King's College, Strand. 



Prof. Gates's restatement of certain points in his 

 original argument, if more explicit, nevertheless meets 

 but one of the issues raised in my article. In answer 

 to the doubt therein expressed as to whether he him- 

 self can be held blameless of the offence with which 

 he charges others, he pleads 'not guilty." But if 

 "obscurantism" (the author's word, not mine) be 

 judged too harsh a verdict on the passage cited, 

 obscurum per obscuriiis in respect of this particular 

 statement — and others — is not to be gainsaid. And 

 shall we even then acquit the author on the more 

 serious count? Or will the general reader desirous 

 of comprehending the relation of Mendelian to Dar- 

 winian theory uphold the charge after perusal of the 

 author's introduction? If he do not, he will unques- 

 tionably deserve the encomium which the author, so 

 disarmingly, bestows upon myself. 



The Writer of the Article. 



IVTolluscan Fauna of Scottish Lakes, and a Pisidium 

 New to the British Isles. 



May I through the columns of Nature invite the 

 assistance of naturalists who may be visiting Scottish 

 lakes and tarns on their holidays in making known 

 the moUuscan contents? 



Whilst Mr. R. A. Phillips and Mr. Stelfox have 

 investigated the moUusca of the Irish lakes, and Mr. 

 C. Oldham those of much of Wales and England, 

 our knowledge of the Scottish fauna is lamentably 

 deficient. If living specimens are unobtainable, dead 

 shells from the shores will be acceptable as showing 

 what species are present. In either case, for purposes 

 of identification, no special method of preservation is 



NO. 2701, VOL. 107] 



necessary — the specimens will travel perfectly if packed 

 in sand or sawdust ; but if spirit is procurable fresh 

 specimens would be more useful if placed in that 

 medium. In all cases, of course, locality and date 

 are essential. 



As instancing the interest attaching to the investigu- 

 tion, and the possibility of further important dis- 

 coveries, I may mention that Dr. Nils Hj. Odhner, 

 of the Rijksmuseum, Stockholm, has just identified 

 some specimens from Loch Ness, in my collection, 

 as being Pisidium clessini, Surbeck, a deep, cold- 

 water species known also from Sweden and Switzer- 

 land, which he has also recognised from two other 

 British localities. B. B. Woodward. 



4 Longfield Road, Ealing, London, W.5. 



Cup and Ring Markings. 



In reply to Mr. Abbott's letter in Nature of July 21, 

 p. 652, I regret that he did not see the photographs 

 to which I referred ; had he done so he would have 

 appreciated the difference between these and his own. 

 As there is no tangible evidence that such recon- 

 structed surfaces are due either to gelic selection or 

 adsgrptive precipitation, I submit that, pending the 

 proving of the gel theory, it is safer to describe the 

 process as " concretion ar}-, " for this term covers much 

 ignorance, and is, at least, non-committal. 



May I say that the ridged mortar, as shown in Mr. 

 Abbott's interesting photograph, is not found only on 

 the northern sides of buildings near the sea ; I have 

 excellent examples from Corfe Castle and other build- 

 ings in the district, from old field-walls at Kirkby 

 Lonsdale, and from many other places inland? 



There is a coign of calcareous sandstone in the wall 

 of an old barn a few miles from Kirkby Lonsdale 

 with the whole surface naturallv ridged and ringed, 

 while the mortar surrounding it is unaltered. 



I have never suggested that similar patterns were 

 not carved on some rock surfaces by prehistoric man, 

 but that, if they were, - these mystic markings were 

 copied from Nature long before the days of mortar ! 



I regret I am now unable to find the photographs 

 of 1896, but when I do Mr. Abbott shall see them. 



C. Carus- Wilson. 



Science and Civilisation. 



The letter of Mr. Henderson Smith and Major 

 A. G, Church in Nature of July 28, p. 684, is most 

 welcome as showing that scientific workers are at last 

 beginning to realise that it is time for science to make 

 itself felt, not only for the acquisition of knowledge 

 and the improvement of machinery and production, 

 but also for the establishment of a national and har- 

 monious social order. 



May I say that a scheme has already been evolved 

 which should appeal to all truly scientific sociologists? 

 It is based essentially on economic and eugenic prin- 

 ciples, and is termed Neo-Malthusianism. It aims at 

 eliminating poverty and other social evils by propor- 

 tioning population to the means of subsistence, and 

 at securing race improvement by maintaining the 

 selective struggle of Darwin, substituting humane 

 voluntary abstention from reproduction for brutal 

 elimination by disease and starvation. It aims also 

 at the elimination of class and international warfare 

 through the diminution of the pressure of population, 

 and at the reduction of vice and disease by promoting 

 universal early marriage. 



Anyone interested in this subject is invited to write 

 to the hon. secretary of the Malthusian League, 

 124 Victoria Street, S.W.i. 



C, V. Drysdale. 



