January 26, 191 1] 



NATURE 



405 



National Association for the Prevention of Tuber- 

 culosis. The trumpet-call is shdrt, but its clear notes 

 should inspire confidence in the ranks of the small 

 army now fighting against ignorance and disease. 



G. 



Weather Instruments and How to Use Them. By 

 D. VV. Horner. Pp. 48. (London : Witherby and 

 Co., 19 10.) Price 6d. net. 

 This handy little work is intended chiefly for 

 amateurs, but it includes descriptions of instruments 

 required for a " second-order " station, while difficul- 

 ties which the author thinks are apt to " scare off " 

 novices are avoided. It contains much that is in- 

 teresting and useful, but its reading leaves us with 

 the impression that persons wishing to take up the 

 ■subject seriously might at once turn to the handbooks 

 ind instructions issued by recognised authorities, 

 ^ome instruments and methods not suitable for 

 econd-order stations are also included, and, naturallv 

 ill so small a work, no tables are given. Under air- 

 pressure the necessity of using accurate barometers is 

 pointed out. Reference is also made to the so-called 

 Fitz-Roy barometer, which, like the Gladstone bag. 

 Is, we believe, only a trade name ; as it is easilv read, 

 it may. however, be useful to the ordinary individual, 

 who merely uses the barometer as a " weather glass." 



Killing's Press Guide and Advertisers' Directory and 



Handbook, 1911. Pp. xiv + 457. (London: James 



Willing, Jun.. Ltd.) Price js. 



This is the thirty-eighth year in which this concise 



j and comprehensive index to the Press of the United 



i Kingdom has appeared. The volume also contains a 



! list of the principal colonial and foreign journals and 



a variety- of general information. 



Field and Colliery Surveying. A Primer Designed for 

 the Use of Students of Surveying and Colliery 

 Manager Aspirants. By T. A. O 'Donahue. Pp. 

 xii + 263. (London: Macmillan and Co., Ltd., 1911.) 

 Price 3s. 6d. 

 A REVISED and enlarged edition of this book was pub- 

 lished in 1909, under the title, "Colliery Surveying." 

 The opportunity has been taken with this new issue 

 to make further additions and to change the title so 

 as to direct attention to the prominence given in the 

 work to field surveying. 



Solutions of the Examples in an Elementary Treatise 

 on Conic Sections by the Methods of Coordinate 

 Geometry. By Charles Smith. Pp. ivH-377. 

 (London : Macmillan and Co., Ltd., 1910.) Price 

 I05. 6d. 

 The master of Sidney Sussex College, Cambridge, 

 here provides a "key" to the examples in the new 

 edition of his "Treatise on Conic Sections bv the 

 Methods of Coordinate Geometrv," published re- 

 cently. 



T.a Metallographie appliquee aux produits Siderur- 

 giques. By U. Savoia. Pp. x + 218. (Paris: 

 Gauthier-Viilars, 1911.) Price 3.50 francs. 

 This is a French translation from the Italian, and 

 as the English equivalent has already been noticed in 

 Nature (December 15, 19 10, p. 202) nothing further 

 need be said, except that the work of rendering into 

 French seems to have been carefully done, and that 

 there are altogether ninetv-four- illustrations in the 

 text. 



Key to Hall and Stevens's School .Arithmetic. Part II. 

 By L. W. Grenville. Pp. 174. (London : Mac- 

 millan and Co., Ltd., 19 10.) Price 6s. 

 Busy teachers, and students working alone, will wel- 

 come these well-arranged solutions to the examples 

 va the second part of Messrs. Hall and Stevens's 

 "School .Arithmetic." 



NO. 2152, VOL. 85] 



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 intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



The Inheritance of Acquired Characters. 



In his very friendly notice of my little book. Prof. 

 Meldola has invited readers of Nature to furnish an 

 explanation of the source of a very " pregnant " passage 

 — the only one dealing with the subject in question — in 

 the " Origin of Species." Sir \V. T. Thiselton-Dyer has 

 clearly shown that the problem must certainly have been 

 in Darwin's mind at least four years before the writing 

 of the " Origin," when he was absorbed in the reading of 

 the great work of .Alph. de Candolle, and afterwards while 

 writing tlie " \'ariations of .■\nimals and Plants." 



But, thanks to that important work, " The Founda- 

 tions of the Origin of Species " — by the publication of 

 which Dr. Francis Darwin has placed all students of the 

 history of science under such deep obligations — I think it 

 is possible to trace the actual " genealogy " of the passage, 

 and to detect its origin, at a far earlier period. 



In the pencil-written sketch of 1842 there occurs the 

 following sentence in the equivalent position to the passage 

 in question : — 



" Most of these slight variations tend to become 

 hereditary " (" Foundations," p. i). 



It is true that this sentence was erased by Darwin, but 

 that this erasure was only due to the fact that he con- 

 sidered it unessential in the very brief outline of tlie 

 theory of natural selection which he then " permitted " 

 himself to make is, I think, proved by the circumstance 

 that the statement appears in the enlarged and carefully- 

 written draft of 1844 in the following terms : — 



" Most organic beings in a state of nature vary exceed- 

 ingly little : I put out of the case variations (as stunted 

 plants, &c., and sea-shells in brackish water) which are 

 directly the effect of external agencies and which we do 

 not know are in the breed or are hereditary " (" Founda- 

 tions," p. 81}. 



The italics are Darwin's own. The context, I think, 

 proves that " little " in this passage, like " slight " in 

 the earlier one, refers to the individual variations, and 

 not to their accumulated result. 



In the first edition of the " Origin," and in all sub- 

 sequent editions, as Sir W. T. Thiselton-Dyer points out, 

 the statement runs : — 



" Some authors use the term ' variation ' in a technical 

 sense, as implying a modification directly due to the 

 physical conditions of life ; and ' variations ' in this sense 

 are supposed not to be inherited " ; he then goes on to 

 refer to dwarfed shells, &c. 



Now to realise what was at the back of Darwin's mind 

 in writing these several passages, I think we must go 

 back to the great controversy at the beginning of last 

 century between Cuvier and his followers and the 

 adherents of poor old Lamarck. The position taken up 

 b\- the anti-evolutionists was that^ while they admitted 

 the transmission by inheritance of small variations, they 

 stoutly denied that great changes in structure and habit, 

 such as were required by Lamarck's theory, could be so 

 transmitted. 



Lyell. when he first read Lamarck's great work in 

 1827, was greatly fascinated by it, and down to 1830, and 

 some time after that, became convinced (as his letters to 

 Sedgwick, Whewell, and Herschel show) of the truth of 

 the doctrine of organic evolution. But, as was the case 

 with Darwin, a few years later, his ideas on the subject 

 underwent many vacillations. He paid frequent, and 

 sometimes prolonged, visits to Paris, where Cuvier showed 

 him much kindness, inviting him to his receptions. Lvell, 

 then still young and an ardent admirer of Cuvier's 

 palaeontological work, could not fail to be impressed by 

 the arguments of the distinguished Paris circle, and we 

 especially find that their studies of the Egyptian 

 mummified animals and of the anatomy of the races of 

 dogs had a very strong influence on his mind. Thus it 

 came about that in 1832, when he wrote the second 



