ESSAYS ON EVOLUTION. 



485 



History of Mankind" (2nd Ed. 1826) "anticipated in the clearest 

 manner the arguments which have been recently advanced by Weismann 

 in favour of the non-transmission of acquired characters." * The following 

 sentence is exactly such as the present Darwinian followers of Weismann 

 write : " Whatever varieties are produced in the race, have their begin- 

 ning in the original structure of some particular ovum or germ, and 

 not in any qualities superinduced by external causes in the progress of 

 development." f 



But " Prichard subsequently reconsidered all his suggested causes of 

 variation and was dissatisfied with them ; ... for the influence of 

 climate seemed to him the most important of all causes of race- 

 formation." In fact he appears to have forestalled the conclusions 

 of ecologists of to-day ; and, like Darwin himself, who superadded, if 

 he did not put on one side, his primary theory of indefinite variations, 

 which natural selection requires, for definite variations which require 

 no selection at all, Prichard thus writes : " Is it not probable that 

 the varieties which spring up within the limits of particular species 

 are further adaptations of structure to the circumstances under which 

 the tribe is destined to exist?" Professor Poulton adds: "It is clear 

 that the writer held a view similar to that which has been termed 

 ' self-adaptation ' by some modern writers — viz. that external influences 

 act on the organism in such a manner as to evoke directly a favourable 

 response." t 



Prichard observes how "individuals and families, and even whole 

 colonies, perish and disappear in climates for which they are by 

 peculiarity of constitution not adapted." " We have here," writes 

 Professor Poulton, " the undoubted recognition of natural selection." 

 But the professor fails to see that he is extending the meaning beyond 

 that which Darwin gave to it — viz. the survival of the fittest out of a 

 mixture of adaptive and inadaptive variations. 



If one takes a number of seeds of tropical plants and sows them 

 in the Arctic regions, even if they germinated, they would undoubtedly 

 all perish, not because of their developing "injurious" characters, but 

 because the living protoplasm has not adapted itself to bear a tempe- 

 rature below freezing ; whereas the protoplasm of Arctic plants can stand 

 freezing ; so that a herb in full blossom may be frozen hard and be quite 

 brittle, yet as soon as the temperature rises it will continue where it 

 left off blossoming and fruiting. All this is not at all in correspondence 

 with Darwin's description of natural selection. § 



Finally, Professor Poulton observes : " He is so fascinated by the 

 view of a local influence directly producing adaptation that he throws over 

 much that he had prevously argued for in a most convincing manner." 

 The fact is, that . as soon as any observer realizes the force of a single 

 instance he will be "invincibly " led (as M. Costantin says) to accept the 

 view of direct adaptation. || 



From page 203 to the end of the book (p. 393) the author deals with 

 mimicry in insects, and refers all the phenomena to the explanation by 



* Loc. ext. p. 174. f Loc. cit. p. 183. 



J Henslow, Heredity of Acquired Characters, p. 190. 



§ Origin, dc. 6th Ed. p. 63. || Les Vege'taux et les Milieux Cosmiqtic*. 



