June 13, 1901] 



NA TURE 



147 



it was a mere affair of outposts compared with the cam- 

 paign that was to follow. He tells us : — 



" I was not brought into serious contact with the 

 ' species' question until after 1850. At that time I had 

 long done with the Pentateuchal cosmogony .... from 

 which it had cost me many a struggle to get free '' (i. 167). 



Later on he calls " the hypothesis of special creation 

 .... a mere specious mark for our ignorance" (ii. 302). 

 What was to be put in its place ? Herbert Spencer, 

 whose acquaintance he made in 1852, was unable to con- 

 vert him to evolution (i. 168). He could not bring him- 

 self to acceptance of the theory — owing, no doubt, to his 

 rooted dislike to a priori reasoning — without a mechanical 

 conception of its mode of operation. Like Darwin, he 

 derived no comfort from either Lamarck or the "Vestiges" 

 (i. 168). For the former, nevertheless, he always enter- 

 tained the most profound respect, and thought he would 

 run Darwin "hard both" in genius and fertility'' (ii. 39). 

 His review of the latter was the only one he ever had 

 " qualms of conscience about on the grounds of needless 

 savagery" (i. 168). 



His attitude to evolution continued to remain altogether 

 sceptical and stand-off. In his first interview with Dar- 

 win, which seems to have been about 1852, he expressed 

 his belief "in the sharpness of the lines of demarcation 

 between natural groups," and was received with a 

 " humourous smile " (i. 169). Hooker, on the other hand, 

 he thought '■'■capable de tout in the way of advocating 

 evolution" (i. 170) ; but then Hooker was in the secret. 



Before continuing the story I think it will be helpful to 

 state in simple terms the problem that Darwin attempted 

 to solve, and to which he got his first clue in the Gala- 

 pagos. Take a number of organisms at random and pro- 

 ceed to sort them according to their resemblances. When 

 this has been done it will be found that they have fallen 

 into groups larger or smaller, as the case may be. The 

 members of the groups will closely agree in all essential 

 particulars ; they are indiz'idua/s. Yet no two are exactly 

 alike ; this is variation. Yet within the group there will 

 be nothing to oppose the view that each may pass into 

 the other ; the variation is continuous. This will not be 

 the case in comparing groups themselves ; the variation 

 is more marked and discontinuous. The discontinuity 

 can be expressed in technical terms, and these give us an 

 abstract definition of the species or the distinctive marks 

 common to the individuals forming the group. Treatino- 

 species in the same way we arrive at a series of discon- 

 tinuous groups of a higher order ; these are genera. 

 Continuing the process we obtain families. Proceeding 

 onwards in the scale we find ourselves face to face with 

 two, perhaps the most difiicult of all to define— the Vege- 

 table and Animal kingdoms. 



Now Darwin, of course, saw with every one else that if 

 the mode of origin of groups of the first order could be 

 explained, all the rest followed. What was wanted was 

 the discovery of some intelligible agency which could 

 effect the passage of one organic form to another. As 

 Huxley put it : — 



"That which we were looking for, and could not find, 

 was a hypothesis respecting the origin of known organic 

 forms which assumed the operation of no causes but such 

 as could be proved to be actually at work" (i. 170). 

 NO. 1650, VOL. 64J 



Darwin assumed continuous variation as an empirical 

 fact and " natural selection " as the agency which had 

 directed the course of organic evolution. This was a 

 generalised form of the "artificial selection " which the culti- 

 vator and the breeder use every day in moulding organic 

 nature pretty much as they will. As Huxley says :— 



" My reflection when I first made myself master of the 

 central idea of the "Origin" was, ' How extremely stupid 

 not to have thought of that '" (i. 170). 



Huxley's attitude to Darwinism deserves careful study. 

 Some have thought that in his last public appearance at 

 Oxford in 1894 he hinted his willingness to make a 

 present of Darwin's theory to Lord Salisbury, as organic 

 evolution could be established without it. And no doubt 

 that is a view which can be maintained. Lord Salisbury 

 had ridiculed the idea of the advantageous male in 

 pursuit of the advantageous mate. This only showed 

 that he could have studied Darwin to very little purpose. 

 I am not one of those who think that the discontinuous 

 "sport," advantageous or not, has played much part 

 in evolution. But in any case its appropriate pairing is 

 not essential, as it is now known that sports are frequently 

 prepotent and their influence not easily swamped. The 

 unmatched advantageous male is not so easily dismissed 

 as Lord Salisbury seemed to think. 



Huxley found in Darwin what he had failed to find in 

 Lamarck, an intelligible hypothesis good enough as a 

 working basis. But with the transparent candour which 

 was characteristic of him he never to the end of 

 his life concealed the fact that he thought it wanting in 

 rigorous proof. 



Now Darwin was a naturalist, and the " Origin " is 

 emphatically the production of a naturalist. Huxley has 

 repeatedly told us, what is perfectly true, that he was not 

 one himself "His love of nature had never run to 

 collecting either plants or animals " (ii. 443). For him 

 as for others Lyell " was the chief agent in smoothing 

 the road to Darwin" (i. 168), for evolution is implied in 

 uniformitarianism. Huxley was an anatomist, and the 

 distinctions of the higher groups with which he chiefly 

 occupied himself -are anatomical. The discontinuity of 

 those groups no longer troubled him now tlAt he knew 

 what lay behind Darwin's "humourous smile." But with 

 "species" or primary groups he still found difficulties 

 which I think he would not have found if he had had a 

 naturalist's experience. At Edinburgh : — 



"In common fairness he v/arned his audience of the 

 one missing link in the chain of evidence — the fact that 

 selective breeding has not yet produced species sterile to 

 one another" (i. 193). 



He states the point more precisely in a letter to 

 Kingsley : — 



" He (Darwin) has shown that selective breeding is a 

 vera causa for morphological species ; he has not yet 

 shown that it is a vera causa for physiological species " 

 (i- 239). 



Now it seems to me that, to use one of his own favourite 

 expressions, this is a shadow of the mind's own throwing. 

 The species which Darwin undertook to account for 

 are morphological. No other category conveys any 

 meaning. There is a physiological difference between 

 the sweet and bitter almond, because one is harmless and 



