Sept. 20, 1883] 



NA TURE 



485 



tell of some contests for priority. All pure mathematics 

 consists in the drawing out of ideas latent in admitted 

 principles, and it is a curious fact how men will fail to 

 draw the consequences which to another will appear 

 irresistibly suggested by something they have themselves 

 asserted, and consequently how near they will come to 

 the brink of a discovery without actually making it. And 

 con'roversies as to mathematical priority naturally arise 

 because it seems so cruel to the man who has taken all 

 the steps except the very last, that another should step in 

 and get the credit of the discovery, when it seems to him 

 that he himself had done all the difficult part of the work 

 and the other only drawn an inference so simple that no 

 credit should be given to any one for making it. If no 

 controversy of the kind has arisen in the present case, 

 perhaps the cause is not exclusively the indisputable 

 character of Cayley's claims, but something is also due to 

 the moral nature of the man. His motto has always 

 been " esse quam videri," and I do not know any one to 

 whom it would be more repulsive to engage in a personal 

 contest by claiming for himself a particle of honour or of 

 money more than was spontaneously conceded. He would 

 be apt to take for his model the patriarch Isaac, who, 

 when the Philistines claimed a well which he had dug, 

 went on and dug another, and when they claimed that 

 too, went on and dug a third. 



The place of a more minute account of his mathe- 

 matical discoveries may be supplied by a mention of 

 the wide recognition which his labours have received. 

 He was given the honorary degrees of D.C.L. Oxford, 1864, 

 LL.D. Dublin, 1865, and was elected Fellow or Corre- 

 spondent of the following Societies : — Philosophical So- 

 ciety, Manchester, 1859; French Institute, 1863 ; Royal 

 Societies, Edinburgh and Berlin, 1865 ; Boston, 1866 ; 

 appointed a Member of the Board of Visitors, Greenwich 

 Observatory, 1866; Milan, 1868; St. Petersburg and 

 Gottingen, 1S71 ; Royal Irish Academy, 1873; Upsala, 

 Leyden, and Rome, 1875 ; Hungary, 1881 ; Sweden, 

 1882. I should add that the Royal Society awarded him 

 a Royal Medal in 1859, and last year (1882) the Copley 

 Medal ; the latter a distinction seldom conferred on a 

 pure mathematician. 



Though his principal interests are mathematical, they 

 are far from being exclusively so. He is a good linguist, 

 and, as was said of Moltke, there are few European 

 languages in which he does not know how to hold his 

 tongue. He is chairman of the Association for Pro- 

 moting the Higher Education of Women. When seats 

 in the University Council are contested, his name always 

 appears on both the rival lists. By all who know him he 

 is as much respected as a high-minded man as he is 

 admired as a mathematician. George Salmon 



BENTHAM AND HOOKER'S " GENERA 

 PLANTARUM" 

 Genera Plantarum ad exemplaria imprimis in lierbariis 

 Kewensibus servata definita. By G. Bentham and 

 J. D. Hooker. 3 vols. (London, 1S62-1883.) 

 "J"" HE completion of the "Genera Plantarum" of Messrs. 

 -*- Bentham and Hooker, an event long impatiently 

 desired by all botanists, has been recently effected by the 

 publication of the second and concluding part of the third 



volume. This great work has required more than five- 

 and-twenty years of assiduous labour, during which the 

 authors have devoted themselves to their formidable task 

 with untiring perseverance, and with a degree of unity 

 both in the plan and the execution of the work which 

 would have been impossible but for their constant daily 

 intercourse, and their relations of intimate personal 

 friendship. 



Before undertaking the publication of the " Genera " its 

 authors had already given to the world important works 

 which had placed them in the foremost rank as botanists, 

 and both were familiarly acquainted with the scientific 

 wealth accumulated in the museums and gardens at Kew- 

 Mr. Bentham, whose botanical collections were united to 

 those of the Royal Herbarium as long as thirty-six years 

 ago, had already in connection with his various works 

 and memoirs had occasion to study nearly the entire 

 vegetable kingdom ; while Sir Joseph Hooker, in addition 

 to an equally wide range of study, had the inestimable 

 advantage of having during his extensive travels been 

 able to observe in the living state numerous species of 

 many genera characteristic of the tropical and antarctic 

 regions, and of having fixed their analytical characters by 

 sketches and diagrams of singular elegance and accuracy. 



With a rare amount of abnegation of personal feeling 

 the authors of this work were content to let it go forth 

 under their joint names, without in any way indicating 

 the separate share contributed by each of them, desiring, 

 as it would appear, that it should be regarded as the col- 

 lective result of their joint labours — the product cf two 

 minds working harmoniously for a common object. Only 

 very recently, under the pressure of urgent requests from 

 many different quarters, Mr. Bentham consented, in a 

 short note communicated to the Linnean Society, 1 to 

 explain in a summary way the share contributed by each 

 of the authors. This is of so much interest to botanists 

 that the present writer does not hesitate to give here the 

 substance of Mr. Bentham's note. 



The Polypetalce, which fill the first volume, were pretty 

 equally divided. While Mr. Bentham was engaged on 

 the earlier orders, Sir J. Hooker undertook the Crucifcra, 

 Capparideee, and Resedacece ; and to his share also fell 

 most of the numerous families of the DisciJlora>, while 

 Mr. Bentham elaborated the remaining families of the 

 Thalamiflorce, along with the Linecr, Humiriaceez, Gera- 

 niacece, and Olacinccr. Of the group of the Calyciflora: 

 it was natural that Mr. Bentham should undertake the 

 Leguminostz, which he had already illustrated by a series 

 of important memoirs, and to him also fell the Myrtacea, 

 Umbet/ifera, and Araliaccce. The remaining families of 

 this group, including the Rosacea, Saxifragea, Melasto- 

 macca, and Cucurbiiacea', besides many others less im- 

 portant, were assigned to Sir J. Hooker. 



The first portion of the second volume is almost 

 entirely occupied by the two great families of Rubiaceee 

 and Composite. To the former of these Sir J. Hooker 

 devoted two years of constant study which involved very 

 numerous dissections of a difficult nature, and he also 

 elaborated the Caprifoliacea. During the same period 

 Mr. Bentham was mainly occupied with the vast family ot 

 Composites, comprising nearly 800 genera, and not much 



1 "On the joint and separate w:>rk of the authors of Bentham and Hooker's 

 ' Genera Plantarum.' " Journal of the Linnean Society— Botany, vol. xx. 

 pp. 304-308. 



