February 



.896] 



NATURE 



355 



unauthorised and unscientific intrusion ; because it gives oppor- 

 tunity for the pure litterateur to pose as a theorist. The specu- 

 lations of the physicist or chemist are, moreover, generally 

 expressed in a symbolical language which is not understood by 

 the public at large, and their ideas, however revolutionary, thus 

 escape newspaper and magazine notoriety. As far as my read- 

 ing extends, I am inclined to believe that even in the case of the 

 purely literary treatment of biological problems by writers who 

 are not experts, the danger of overweighting the science with 

 hypothesis is much exaggerated. Writers of this class are often 

 capable of taking a wider and more philosophic grasp of a 

 problem than a pure specialist, and ideas of lasting value have 

 sometimes emanated from such sources. I imagine that nobody 

 will dispute that Mr. Herbert Spencer's writings have largely 

 influenced the public mind — whether we agree with the details 

 of his doctrines or not — in accepting the broad principle of 

 evolution, although this profound thinker lays no claim to an 

 expert knowledge of any branch of natural history. But every 

 working naturalist can ascertain for himself the credentials of 

 any particular writer : my remarks are simply offered with the 

 object of claiming more consideration for such writers, as a 

 class, on the part of practical workers. The philosophic faculty 

 is quite as powerful an agent in the advancement of science 

 as the gift of acquiring new knowledge by observation and 

 experiment. It is not often that the faculties are combined in 

 one imlividual. 



The general conclusion to which these considerations point is 

 that the biological theorist, by virtue of the complexity of the 

 factors, the difficulty of experimental verification, and the 

 tendency on the part of the public to mistake tentative 

 hypotheses for established theories, should put forward his 

 views with more explicit caution than is necessary in the case 

 of the physical sciences, where experimental evidence is more 

 easily obtainable, and where the self-constituted philosopher 

 but rarely gets a hearing. All this amounts, however, to 

 nothing more than a plea for caution, and not for total absti- 

 nence. To disallow speculation because a complete theory 

 cannot be formed out of the existing materials, is simply to put 

 a check upon legitimate advancement. I freely admit that it is 

 possible to carry .speculation to an unscientific extreme— to 

 fritter avNay a plausible hypothesis by mere metaphysical dis- 

 cussion, or to bury a real and important issue under an incubus 

 of verbiage. But this is not the legitimate use of the speculative 

 method ; it is an accident, which the scientific worker will know 

 how to avoid, and which is contingent upon the present con- 

 dition of biological investigation. We cannot test our specu- 

 lations oft-hand by a few crucial experiments, as in physical 

 science, and in the meantime the logic-chopper may get hold of 

 our idea and whittle it away. On these grounds, however, I 

 again fail to see any reason for repressing spToculation. It might 

 as well be argued that because the action of fire, carried to an 

 extreme, carbonises organic matter, we should therefore eat 

 our food raw. The irresponsible manipulation of biological 

 hypotheses by pure speculators does no real or permanent injury 

 to the cause of science, and may indirectly do good by directing 

 public attention to the work which is being carried on. I 

 rather think the absence of public sympathy, in connection with 

 theoretical research in chemistry and physics, exerts a depressing 

 influence ; the inventor of a new hypothesis in these subjects 

 moves entirely in an atmosphere of his own creation, which even 

 his colleagues seldom venture to penetrate. That biological 

 speculations are more prone to such unauthorised treatment is no 

 more a reason for refusing to speculate than the circumstance 

 that generations of fact-collectors have wasted their time in 

 amassing large stores of disconnected observations, which for 

 want of system are practically of no avail to the scientific worker, 

 is an argument in favour of repressing observation. It is 

 possible to be quite as unscientific in the accumulation of facts as 

 it is to become metaphysical by over-speculation ; there is as 

 much danger in one direction as there is in the other. Yet the 

 most ardent advocate of the theoretical method has not taken it 

 upon himself to declare that observation must cease until he has 

 explained all the facts at present available. This, however, is 

 practically the position taken up by those who refuse to recognise 

 that existing knowledge is sufficient to enable considerable 

 advance to be made by the legitimate use of the theoretical 

 method. 



One other point demands consideration, in conclusion. If 

 latitude for the exercise of speculation is to be allowed, where, it 

 may be asked, is the line to be drawn ? How are we to dis- 



NO. 1372, VOL. 53] 



tinguish between the cautious theoriser and the writer who permits 

 himself " unlxjunded license?" These are questions to answer 

 which requires nothing but an exercise of individual judgment. A 

 sound speculation may emanate from the happy possessor of a 

 philosophic mind although he may never have done any technical 

 biological work. But this kind of speculator naturally fails to 

 secure that hearing to which the practical worker is entitled. 

 Although valuable generalisations may occasionally be given 

 out by great thinkers, the expert biologist shows wisdom in 

 giving his most serious attention only to those who are familiar 

 with their data at first hand— who have themselves gleaned 

 their information directly from nature. By such workers only 

 can the true value of the evidence be fairly weighed and esti- 

 mated. I should be very sorry if the remarks which I have 

 ventured to offer in the course of this address were to be inter- 

 preted into a general public invitation to speculate on biological 

 problems. But I do raise the question here as to the kind of 

 biological work which is to be recognised as a fitting preparation 

 for the exercise of the speculative faculty. It used formerly to 

 be asserted that he only is worthy of attention who has done 

 systematic, i.e. taxonomic, work. I do not know whether this 

 view is still entertained by entomologists ; if so, I feel bound to 

 express my dissent. It has been pointed out that the great 

 theorisers have all done such work — that Darwin monographed 

 the Cirripedia, and Huxley the oceanic Hydrozoa, and it has 

 been said that Wallace's and Bates's contributions in this field 

 have been their biological salvation. I yield to nobody in my 

 recognition of the value and importance of taxonomic work, but 

 the possibilities of biological investigation have developed to 

 such an extent since Darwin's time that I do not think this 

 position can any longer be seriously maintained. It must be 

 borne in mind that the illustrious author of the " Origin of 

 Species " had none of the opportunities for systematic training 

 in biology which any student can now avail himself of. To him 

 the monographing of the Cirripedia was, as Huxley states in a 

 communication to Francis Darwin, "a piece of critical self- 

 discipline," ' and there can be no reasonable doubt that this 

 value of systematic work will be generally conceded. That this 

 kind of work gives the sole right to speculate at the present time 

 is, however, quite another point. It might be argued with some 

 show of reason that exclusive devotion to systematic work 

 cripples the imaginative faculty.^ The methods of attacking the 

 problems connected with living organisms have been increased 

 and improved from every side, and the anatomist and physio- 

 logist, the morphologist, the embr)'ologist, the student of 

 bionomics, have all an equal claim to contribute to biological 

 theory. The particular problems relating to the transformation 

 of species are no doubt best dealt with by those who, by syste- 

 matic work, have acquired a true notion of what is meant by the 

 term "species." But so far as entomology is concerned, it 

 must be confessed that the greater part of our systematic work 

 has emanated from cabinet entomologists, who know nothing of 

 the species they describe as living organisms by direct observa- 

 tion, and to me it appears doubtful whether this kind of work 

 does confer any special faculty of speculating with advantage on 

 the species question. It seems rather that the " field-naturalist" 

 in the old sense of the term has the advantage, and I may remind 

 you in this connection that during the voyage of the Beagle, when 

 Darwin began to make those observations on island life which 

 afterwards led him to take up the question of species transforma- 

 tion, he was essentially a " field-naturalist," his systematic work 

 on the Cirripedia not having been commenced till after his 

 return. So also Wallace, at the time when he independently 

 elaborated the theory of natural selection, was certainly not a 

 systematist in this narrow sense. He has been good enough to 

 favour me with his views on this point, in a letter dated 

 December 31, 1895, in which he says: " I do not think species- 

 describing is of any special use to the philosophical generaliser, 

 but I do think the collecting, naming, and classifying some 

 extensive group of organisms is of great use, is, in fact, almost 

 essential to any thorough grasp of the whole subject of the 

 evolution of species through variation and natural selection. I . 

 had described nothing when I wrote my papers on variation, &c. 

 (except a few fishes and palms from the Amazon), but I had 

 collected and made out species very largely, and had seen to 



1 " Life and Letters," vol. i. p. 348. Even in the days of my studentshi p 

 Huxley lectured on Natural History at the Royal School of Mines with the 

 aid of diagrams and specimens only : practical work in the laboratory- was 

 unknown. 



2 See a letter from Darwin to Bates in 1861, "Life and Letters," vol. ii. 

 P- 379- 



