784 POPULAR SCIENCE MONTHLY. 



The result of comparative study of the lower forms of life is 

 suggestive in this connection.* With plants and animals a sud- 

 den change of habitat will often produce a temporary sterility, 

 which disappears only after a series of chance variations. The 

 chrysanthemum remained infertile for sixty years after its intro- 

 duction into France from China, so that continued importation of 

 the seed was necessary. Finally, in 1852 a few plants developed 

 seeds ; and from these others were raised, until to-day the species 

 is self-sustaining in Europe. A similar experience with corn at 

 Sierra Leone, with the goose at Bogota, and European poultry in 

 America, is instanced by De Quatrefages.f His rather optimistic 

 argument with regard to the future of acclimatization is based, 

 indeed, upon the study of animals and plants, rather than of man. 

 He reasons by analogy that if fertility becomes re-established by 

 spontaneous variation in this sphere, it may be likewise affirmed 

 to be true for man, thus giving countenance to the view that cli- 

 matic changes do indeed produce infertility. 



Despite the authorities who hold on general principles that 

 sterility in man follows or at least that it ought to follow a sud- 

 den change of climate, direct proof for it is very hard to find. Broca 

 has indeed affirmed that the Mamelukes in Egypt became infer- 

 tile for that reason ; J but in his case, as in all others, no attempt is 

 made to eliminate a number of other factors. Jousset declares, 

 on the contrary, that no direct efi'ect upon fecundity can be traced 

 to climate.* Dr. Fritsche concedes that, although sterility may 

 result, there is as yet no direct evidence to prove it. || The diffi- 

 culty, it will be observed, is to eliminate the effects of crossing 

 with the natives, or else of marriage with newly arrived immi- 

 grants. A physician of twenty-seven years' experience in the 

 Dutch Indies has never known a European family to keep its 

 blood unmixed in this way for the necessary period of three gen- 

 erations. Only one example of pure isolation is known, in the 

 island of Kisser, and sterility there is by no means certain."^ Ste- 



Prof. Virchow even asserts it to be true in Verhandhingen der Berliner Gesellschaft fiir An- 

 thropologic, 1885, p. 213. It was at the bottom of the exploded theory of Knox and 

 Brace with respect to the decreasing birth-rate in Araerica. Cf. Memoires de la Societe 

 d' Anthropologic, iii, p. 25. 



* Discussed by Wallace in Encyclopedia Britannica. Also for forest trees in Kirchhofif's 

 Forschungen, iii, p. 28 et seq. 



) Op. cit., p. 225. Many other examples are given. Wallace (op. cit.) gives the interest- 

 ing case of the acclimatization of wheat north of the Great Wall by the Emperor of China. 



Ij. Human Hybridity. Cf. the case of the Creoles in the island of St. Louis, cited in 

 Revue d' Anthropologic, new series, v, p. 30 et seq. 



* Op. (it., p. 231. The superior health of women, due to less exposure, has already 

 been noted. 



II Verliandlungen der Berliner Gesellschaft fiir Anthropologic, 1885, p. 258. 

 ^ Ibid., 1886, p. 89. 



