2IO 



HA RD WICKE'S SCIENCE- G OS SIP. 



French naturalist. Mr. Tlatt Ball, in his little 

 book on the "Effects of Use and Disuse," holds 

 this view, and even remarks that " Darwin's belief 

 in the inheritance of acquired characters was more 

 or less hereditary in the family," instancing his 

 father's and grandfather's views on this point. Unless 

 Mr. Ball is prepared to maintain that there was a 

 special inherent predisposition in the Darwin family 

 towards this belief, he is here assuming the inheri- 

 tance of an acquired character ! 



As has been already mentioned, Mr. Darwin 

 attributed more and more importance to this factor in 

 the successive editions of the "Origin," and his opinion 

 on the point culminated in the letter to Professor 

 Wagner already quoted.* It is remarkable too, that he 

 was constrained to form a theory of heredity on the lines 

 of Pangenesis largely to explain these very phenomena. 

 In a letter to Huxley, speaking of his as yet unpub- 

 lished hypothesis of Pangenesis, he says: "I think 

 some such view will have to be adopted, when I call 

 to mind the inherited effects of use and disuse, etc."t 

 Here Darwin was absolutely right. As we shall 

 point out more fully hereafter when discussing possi- 

 ble theories of heredity, "some such view" must 

 be adopted if we believe that the effects of use and 

 disuse are inherited. The naturalists who refused to 

 accept the main idea of " Pangenesis " were trying to 

 maintain an untenable position while they believed 

 in such inheritance. Neither Darwin nor they, 

 however, perceived the only possible alternative — an 

 I alternative which has now been accepted by many — 

 to re-examine the whole grounds of our belief, and 

 boldly declare that definite proof of such inheritance 

 is wanting. This at once casts the ofius probandi 

 upon our opponents, and exempts us from the 

 astounding exercise of faith required to believe in the 

 mechanism of Pangenesis. 



The history of the growth of opinion since 1859 on 

 the subject of the factors of organic evolution is too 

 long a story to be more than touched upon here. 

 But tbe extreme views which have sprung up on 

 both sides, and the complete chain of connection 

 between them are sufficiently remarkable. On the 

 one hand we have the Neo-Lamarckians ; in the 

 main an American school of palaeontologists, (of 

 ■whom Professor Cope is perhaps the best-known 

 member) who reduce the action of natural selection 

 to an almost negligeable minimum, and consider 

 that use and disuse, etc., have been the main agents 

 in the evolution of such structures, for instance, as 

 the mammalian tooth. Professor Eimer in Germany 

 and Mr. Cunningham in England hold somewhat 

 similar views. Then we have a class of biologists 

 like Mr. Patrick Geddes, who believes in natural 



It is collaterally interesting, however, to note that so late 

 as 1881 Darwin was "staggered" (by Hoffman's experiments 

 on the direct effect of conditions on plants) in his views about 

 the increase of variability, especially in cultivated plants, 

 through such direct effects. — "Life," iii. p. 345. 

 ■f" Ibid. iii. p. 44. 



selection to a certain extent, but rather uses it to 

 supplement various more or less ingenious theories 

 of his own, which appear to him to account for the 

 main facts of evolution better than do Darwin's. 



Next we have Mr. Herbert Spencer (and his 

 followers) who stands in a distinctly different position 

 to any of the foregoing, inasmuch as he believed in 

 evolution before 1859, and therefore certainly does 

 not owe from a speculative point of view so much 

 to Darwin's work as do most other people. Mr. 

 Spencer believes, and always did believe, that all 

 organisms are being directly and profoundly affected 

 from moment to moment by the environment, and 

 that the modifications so brought about cannot fail 

 to be transmitted to their offspring. He believes 

 too, that modifications of function in the individual 

 life effect permanent modifications of function and 

 structure in phylogeny (or life of the species) inde- 

 pendently of natural selection. This continual direct 

 attempt, as it were, on the part of an organism 

 to adjust itself to its environment he calls " Direct 

 Equilibration." He accepts the process of natural 

 selection, also, as an important factor, and calls it 

 "Indirect Equilibration," i.e., the indirect process of 

 adjustment to environment, through variation, and 

 the survival of the fittest. 



These are the views enunciated in the " Principles 

 of Biology," and quite lately in two articles in the 

 "Nineteenth Century" for 1886* he has emphasised 

 them, and added new arguments and fuller evidence. 



Professor Burdon-Sanderson has suggested that 

 those who think such factors as the ones specially 

 worked out by Mr. Spencer to be true factors and 

 of extensive application should be called " Spen- 

 cerians " rather than Lamarckians, because, as has 

 already been pointed out, such views as these formed 

 but an insignificant portion of the Lamarckian doc- 

 trine of evolution, while they have always been 

 insisted on as most important by Mr. Spencer, who 

 has, in addition, expressed them in a more general 

 form and widened their meaning and application. 

 The appellation would certainly serve to distinguish 

 the people in question on the one hand from the 

 extreme Neo-Lamarckians, and on the other from 

 true Darwinians. 



Next to the Spencerians we have biologists with 

 views like Professor Romanes, who claim to be the 

 true Darwinians, in holding the position of Darwin's 

 later years. They consider natural selection to be 

 the main factor, but recogni=e various others as 

 supplementary to it, such as "physiological selec- 

 tion," and the effects of other kinds of segregation, 

 either physiological or geographical, and in some 

 cases recognising to a greater or less extent the 

 Spencerian or Lamarckian factors, or else reserving 

 their judgment on this point. Closely following on 

 these, we have, so far as my experience has gone. 



* Reprinted as "The Factors of Organic Evolution." 



