ENVIRONMENTAL SCHOOL OF SOCIOLOGISTS 1@ fe) 
The concluding chapter is given to a study of acclimatization in 
its relation to the problem of the original diversification of races 
from one parent stock, but especially in its bearing on the 
colonization of the tropics by the white race. He shows how 
complex is the question concerning the effect of climate on the 
human organism as when people migrate from temperate regions 
to the tropics,and enumerates several disturbing factors that must 
be eliminated before one can determine this effect, such as the 
natural change in habits of life in the line of intemperance and 
immorality that so frequently accompany army life; the effect of 
race-crossing, choice of foods, differences of occupation with 
indolence on the one hand and over-exertion on the other. He 
shows further how a discussion of the effect of climate on the 
human body must take into consideration the racial element and 
ethnic peculiarities, certain races being susceptible to certain 
diseases and immune to others. Having eliminated these dis- 
turbing elements our author concludes that “ the physical ele- 
ments of climate, ranged in the order of their importance, are 
humidity, heat, and lack of variety.” ! 
Physical acclimatization approximating the adaptation of 
natives, he holds, is a process requiring generations and that ulti- 
mate racial adjustment to the tropics can be secured, if at all, 
only by the costly method of trial and selection or by the drift to 
those regions of individuals and races already by nature and mode 
of life adapted to such life conditions. He shows that much 
temporary advantage may be gained by hygienic precautions, but 
that this does not mean racial acclimatization, and concludes that 
true colonization of the tropics by the white race is impossible.? 
As to the question of the original process of racial acclimatiza- 
tion and diversification, Professor Ripley holds that it was due to 
spontaneous variation and natural selection and possibly also to 
ontogenetic variations that somehow became fastened upon the 
race.$ 
The eminently scientific character of this work and the judicial 
temper evinced on every page make it apparently above adverse 
criticism. The various factors that enter into passive socio- 
1 Races in Europe, p. 571. * Ibid., p. 584. 3 Ibid., p. 587; cf. pp. 383 f. 
