October. 1912. 



KNOWLEDGE. 



403 



however, amended, and it was resolved to construct a new list 

 of genera and species, founded upon Bentham and Hooker's 

 Genera Plantartim. Sir Joseph Hooker was asked by Mr. 

 Darwin to take into consideration the extent and scope of the 

 proposed work, and to suggest the best means of having it 

 executed. He undertook the task, and it was he who laid out 

 the lines to be followed. .After years of labour by Mr. Daydon 

 Jackson and his staff, the work was produced. But Sir Joseph 

 read and narrowly criticised all the proofs. Imagine four 

 large (juarto volumes, containing in the aggregate two thousand 

 five hundred pages, each page bearing three columns of close 

 print, and each column about fifty names. The total figures 

 out to about three hundred and seventy-five thousand specific 

 names, all of which were critically considered by the octogen- 

 arian editor ! Surely no greater technical benefit was ever 

 conferred upon a future generation by the veterans of science 

 than this Index. It smooths the way for every systematist 

 who comes after. It stands as a monument to an intimate 

 friendship. It bears witness to the munificence of Darwin, 

 and the ungrudging personal care of Hooker. 



But the author of great works such as these was still 

 willing to help those of less ambitious flights. I must not 

 omit to mention two books which, being more modest in their 

 scope, have reached the hands of many in this country. In 

 l.S/O Hooker produced his " Student's Flora of the British 

 Islands." of which later editions appeared in 1878 and 1SS4. 

 It was published in order to "supply students and field 

 botanists with a fuller account of the plants of the British 

 Isles than the manuals hitherto in use aim at giving." In 

 1887 he edited, after the death of its author, the fifth edition 

 of Bentham's " Handbook of the British Flora." Both of 

 these still hold the field, though they require to be brought up 

 to date in point of classification and nomenclature. 



I hope I have not wearied you with these brief sketches of 

 four of the great systematic works of Sir Joseph Hooker. I 

 have gone somewhat more into detail than is quite justified in 

 a public speech. But this has been done with a definite end 

 in \iew. It was to show you how fully he was imbued with 

 the old systematic methods : how he advanced, improved and 

 extended them, and was in his time their chief exponent. His 

 father had held a similar position in the generation before 

 him. But the elder Hooker, true to his generation, treated 

 his species as fixed and immutable. He did not generalise 

 from them. His end was attained by their accurate recogni- 

 tion, delineation, description, and classification. The younger 

 Hooker, while in this work he was not a whit behind the best 

 of his predecessors, saw further than they. He was not 

 satisfied with the mere record of species as they were. He 

 sought to penetrate the mystery of the origin of species. In 

 fact, he was not merely a scientific systematist in the older 

 sense. He was a philosophical biologist in the new and 

 nascent sense of the middle period of the nineteenth century. 

 He was an almost life-long friend of Charles Darwin. He 

 was the first confidant of his species theory, and, excepting 

 Wallace, its first whole-hearted adherent. But he was also 

 Darwin's constant and welcome adviser and critic. Well 

 indeed was it for the successful launch of evolutionary theory 

 that old-fashioned systematists took it in hand. Both Darwin 

 and Hooker had wide and detailed knowledge of species as 

 the starting-point of their induction. 



Before we trace the part which Hooker himself played in 

 the drama of evoiutionarj' theory, it will be well to glance at 

 his personal relations with Darwin himself. He had read the 

 proof-sheets of the " Voyage of the ' Beagle ' " while still in his 

 last year of medical study. But before he started for the 

 Antarctic he was introduced to its author. It was in Trafalgar 

 Square, and the interview was brief but cordial. On returning 

 from the Antarctic, correspondence was opened in 1843. In 

 January, 1844. Hooker received the memorable letter confiding 

 to him the germ of the Theory of Descent. Darwin wrote 

 thus: "At last gleams of light have come, and I am almost 

 convinced that species are not lit is like confessing a murder) 

 immutable: — I think I have found (here's presumption!) the 

 simple way by which species become exquisitely adapted to 

 various ends." This was probably the first communication 



by Darwin of his species-theory to any scientific colleague. 

 The correspondence thus happily initiated between Darwin 

 and Hooker is preserved in the " Life and Letters of Charles 

 Darwin." and in the two volumes of " Letters " subsequently 

 published. They show on the one hand the rapid growth 

 of a deep friendship between these two potent minds, 

 which ended only beside the grave of Darwin in Westminster 

 Abbey. But what is more important is that these letters 

 reveal, in a way that none of the published work of either 

 could have done, the steps in the growth of the great 

 generalisation. We read of the doubts of one or the other ; 

 the gradual accumulation of material facts ; the criticisms 

 and amendments in face of new evidence ; and the slow 

 progress from tentative hypothesis to assured belief. We 

 ourselves have grown up since the clash of opinion for and 

 against the mutability of species died down. It is hard for us 

 to understand the strength of the feelings aroused: the bitter- 

 ness of the attack by the opponents of the theory, and the 

 fortitude demanded from its adherents. It is best to obtain 

 evidence on such matters at first hand ; and this is what is 

 supplied by the correspondence between Darwin and Hooker. 

 How complete the understanding between the friends soon 

 became is shown by the provisions made by Darwin for the 

 publication of his manuscripts in case of sudden death. He 

 wrote in August, 1854, the definite direction " Hooker by far 

 the best man to edit my species volume " : and this notwith- 

 standing that he writes to him as a '' stern and awful judge 

 and sceptic." But again, in a letter a few months later, he 

 says to him : " I forgot at the moment that you are the one 

 living soul from whom I have constantly received sympathy." 

 I have already said that Hooker was not only Darwin's first 

 confidant but also the first to accept his theory of mutability 

 of species. But even he did not fully assent to it till after its 

 first publication. The latter point comes out clearly from the 

 letters. In January, 1859, six months after the reading of 

 their joint communications to the Linnaean Society, Darwin 

 writes to Wallace : " You ask about Lyell's frame of mind. 

 I think he is somewhat staggered, but does not give in ... I 

 think he will end by being perverted. Dr. Hooker has 

 become almost as heterodox as you or I, and I look at Hooker 

 as by far the most capable judge in Europe." In September 

 1859 Darwin writes to W. D. Fox: " Lyell has read about 

 half of the volume in clean sheets . . . He is wavering so 

 much about the immutability of species that I expect he will 

 come round. Hooker has come round, and will publish his 

 belief soon." In the following month, writing to Hooker, 

 Darwin says : " I have spoken of you here as a convert 

 made by me : but I know well how much larger the share has 

 been of your own self-thought." .A letter to Wallace of 

 November, 1859, bears this postscript : " I think that I told you 

 before that Hooker is a complete convert. If I can convert 

 Huxley I shall be content." .And lastly, in a letter to 

 W. B. Carpenter, of the same month, Darwin says : " As yet 

 I know only one believer, but I look at him as of the greatest 

 authority, viz.. Hooker." These quotations clearly show that, 

 while Lyell wavered, and Huxley had not yet come in. Hooker 

 was a complete adherent in 1859 to the doctrine of the muta- 

 bility of species. Excepting Wallace, he was the first, in 

 fact, of the great group that stood round Darwin, as he was 

 the last of them to survive. 



The story of the joint communication of Darwin and 

 of Wallace to the Linnaean Society " On the tendency of 

 Species to form Varieties, and on the Perpetuation of 

 Varieties and Species by Natural Means of Selection" 

 will be fresh in the minds of you all, for the fiftieth 

 anniversary of the event was lately celebrated in London. 

 It was Sir Charles Lyell and Sir Joseph Hooker who jointly, 

 and with the authors' permission, communicated the two 

 papers to the society, together with the evidence of the priority 

 of Darwin in the enquiry. Nothing could then have been 

 more apposite than the personal history which Sir Joseph gave 

 at the Darwin-Wallace celebration, held by the Linnaean 

 Society in 1908. He then told, at first hand, the exact circum- 

 stances under which the joint papers were produced. Nor 

 could the expressions used by the President when thanking 



