;66 



NATURE 



[February i6, 1905 



A National University Library. 



It must be the experience of any graduate of Oxford or 

 I ainbridge who is residing at a distance from those univer- 

 sity towns that a serious obstacle to the prosecution of 

 research arises from the impossibility of consulting the 

 university libraries, and the absence of any provision for 

 borrowing volumes, or obtaining references under arrange- 

 ments similar to those pertaining at the libraries of the 

 Royal and other scientific societies. Moreover, while O.xford 

 and Cambridge possess the special privilege of acquiring 

 free copies of books copyrighted in England, there are now 

 many universities in this country which are far too poor 

 to keep up even a decently respectable library in any branch 

 of science. 



The conditions of modern times have created a need for 

 a National University Library, enjoying the same privileges 

 as the Oxford and Cambridge libraries, and which should 

 be available for graduates of any British university ; per- 

 sons engaged in any specified branch of research to have the 

 opportunity of borrowing books through the post as in the 

 case of the Royal Society. G. H. Bryan. 



Mutation. 



The term mutation is applied in biology to that sort of 

 variation in which the equilibrium of the organism seems 

 to be disturbed, and a new position of equilibrium is found, 

 which is markedly different from the original one. This 

 may apply to a whole organism . or merely to some one 

 organ, so far as external appearances show. 



In all the discussions regarding mutation which have 

 lately taken place, the difficulty has been felt that it is 

 impossible by any methods yet known to perceive and 

 measure the internal changes and influences leading to 

 mutability. It is certainly not supposed that mutability is 

 without cause, but it is obviously difficult to detect the 

 causes which bring it about. 



It occurs to me that some help may be obtained from 

 analogies derived from psychology and sociology. What 

 mutation is in biology, conversion is in psychology, and 

 revolution in sociology. It may be said that to assume 

 such parallels is merely to beg the question, but I think 

 that the apparent parallelism cannot be without significance. 

 Now the phenomena leading towards conversion have been 

 studied subjectively (c/. James, " Varieties of Religious 

 Experience "), and those leading towards revolution have 

 been studied objectively, with certain well-defined results. 

 If the supposed analogy is a valid one, it appears to follow 

 that mutability is due to the same general causes 

 as ordinary variability (just as change of opinion 

 and reform are due to the same general causes as con- 

 version and revolution), but that there is this difference — 

 mutability represents an explosion of energy, as it were, in 

 a given direction, and therefore differs from ordinary vari- 

 ation somewhat as the firing of a gun differs from the 

 ixplosion of a loose heap of powder. It also follows that 

 the cause of the explosion is not plasticity in the organism, 

 but in some measure the reverse ; that is, the power of being 

 influenced, and at the same time of withstanding the 

 expression of the influence until it had acquired considerable 

 force. This implies a certain rigidity of type, quite com- 

 parable with a type of mind familiar to all. It further 

 appears to follow that the chance of mutations succeeding 

 from the first is comparatively remote, though such a thing 

 is quite possible ; but since they are the result of general 

 causes, the sort of changes the mutations exhibit arc likely 

 to come about in due course, just as the sort of changes 

 represented by a revolution are likely to prevail ultimately, 

 though the revolution itself may appear to fail. 



T. D. A. C0CKERF.1.L. 



L'niversity of Colorado, Boulder, Colorado, January 25. 



Fact in Sociology. 

 Mr. Wells is a dangerous man to criticise. Such 

 thunderbolts as " crude," " dull," " balderdash," come 

 hurtling at one's head even from his modified letters 

 (Natire, February 2). But 1 prefer to regard it all as 

 meant only for sheet lightning. Indeed, when I consider 

 the courtesy that characterised my article (Nature, 

 December 29), plain-spoken though it was on some points, 

 I cannot take anv other view. 



NO. 1842, VOL. 71] 



Now to Mr. Wells"s points in order. 



(i)"' The Food of the Gods ' does not claim to forecast 

 the future." My mistake was natural. It only shows 

 the risk Mr. Wells runs in appearing before the world 

 in two entirely different characters. Still, I hit upon a 

 weak point. He pictures an ideal State, but cannot show 

 us how ii is to be realised. Archimedes had no fulcrum 

 for the lever with which he would have moved the world. 

 .Mr. Wells has no power to apply to his. 



(21 " / have mixed, up ' A uticipaiioiis ' and ' Mankind in the 

 Making.'" Why keep them separate? " Anticipations " also 

 deals largely with ideals. 



(3) Re the question — Which of the great national 

 " syntheses "will attain predominance, see" Anticipations," 

 chap. viii. passim, and especially pp. 100, 101 (6d. ed., 

 1904). This chapter seemed to me an interesting specula- 

 tion, but Mr. Wells describes what I thought, and, on 

 re-reading, think is to be found in it as " balderdash." 

 True, through inadvertence I wrote " Anglo-Saxon " in- 

 stead of " English-speaking," for which I am sorry. 



(4) lie the recruiting of the upper strata of society from 

 the lower, nothing, he says, is known about this. Still, 

 those who have studied human evolution think they know 

 something. Prof. Karl Pearson even says that there are 

 " class statistics " for the population of Copenhagen, and 

 writes, " the population would accordingly appear to be 

 ultimately, and in the long run, reproducing itself from 

 the artisan classes " (Xatural Science. May, 1896). Dr. 

 Mercier (see the .Sociological Society's papers, 1904, 

 p. 55) regards " a civilised community in the light of a 

 lamp, which burns away at the top and is replenished at 

 the bottom." As to " stagnant " classes, I find in " Anti- 

 cipations," p. 121, " It (the new Republic) will tolerate no 

 dark corners where the people of the .Xbyss may fester, 

 no vast diffused slums of peasant proprietors, no stagnant 

 plague preserves." See especially p. 117 for Mr. Wells's 

 plan for getting rid of undesirable types. .As to careful 

 parentage, see " Mankind in the Making," p. 09: — "The 

 first step to ensuring them (the ends aimed at) is certainly 

 to do all we can to discourage reckless parentage." 



In conclusion, let me describe myself as a much-battered 

 but not unfriendiv critic of the New Republic. 



F. W. H. 



The Melting of Floating Ice. 



May I suggest that Dr. Devcnter, of -Amsterdam, whose 

 letter to you is referred to in your issue of January 26 

 (p. 303), has discovered a " mare's nest "? 



His observant pupil, who noticed that in a glass filled 

 to the brim with water and floating ice the inciting of the 

 latter did not cause overflow, was apparently totally 

 ignorant of the laws of flotation, or he would not have 

 expected otherwise. Why should the level of the water 

 change? The ice in melting must of necessity just fill 

 with water the space that it displaced when floating, and 

 so the level remains unaltered. So Dr. Deventer's state- 

 ment that " when a vessel contains a solid floating in 

 its own liquid, the level of the latter does not change by 

 the melting of the solid " appears quite superfluous. 



.As to making this a " general " law applying to solids 

 floating in their o-,vn liquids, surely the rule is that solids 

 do not do so, but sink. A\'hy make a general law which 

 only applies in the case of a very few exceptional sub- 

 stances, such as ice, cast iron, and bismuth? He.\t. 



Februarv 8th. 



A Lunar Rainbow. 



Last night, after 10 p.m., a thunderstorm passed over 

 this town, travelling from west to east. When the strrni 

 had passed and the rain had almost ceased, a bright quarter- 

 moon shone brilliantly almost overhead. To the east the 

 clouds were still very heavy and dark, and in that direction 

 there appeared a perfect rainbow. The arc of the bow was 

 low ; it appeared as a grey band with a certain suggestion 

 of colour, against the dark leaden sky. ' 



I should be glad to know from any of your readers if 

 such moon rainbows are of common occurrence, as the one 

 of last night is the first which I have seen. 



Pretoria, Transvaal, January 15. J. McCrae. 



