4 SCIENCE PROGRESS. 
with in various races are caused by climatic changes and by 
varying intensity in the rays of the sun, is then considered, 
and a great many ancient and modern exponents of this 
view are quoted. After reproducing a long passage from 
Buffon, the hypotheses of the Rev. Dr. S. S. Smith of 
New Jersey are described. These deal not only with the 
‘gradation in the complexion nearly in proportion to the 
latitude, ...” but also with the influence which heat 
exerts upon the secretion of bile. In consequence of heat 
etne bile... is augmented. . 2.2) Vhisliquonemgesweme 
complexion. . ..” -** Bile, exposed) to the sunvancram are 
known to change its colour to black—black is, therefore, the 
tropical hue.” This latter and the very similar views of 
Blumenbach are, however, dismissed by Prichard as ‘‘ with- 
out foundation” ; while as to the former suggestion of Dr. 
Smith, together with that of Buffon and the older writers, he 
observes that the principal observations on which it is based 
are correct. ‘‘It is certain that the majority of black races 
of men are inhabitants of the intertropical regions, and that 
most of the light-coloured nations are to be found in cold 
or temperate climates.” But although he admits the fact, 
he maintains that it is capable of ‘‘a different interpretation 
from that which modern writers have in general adopted”. 
He similarly admits that the skin of a European is 
darkened by the sun, and continues: “ It seems, at first, not 
very improbable that individuals darkened by exposure to 
heat in southern climates, may have an offspring of deeper 
colour in consequence, and if this effect increases in every 
generation it may be thought sufficient, in a long course of 
ages, to produce a black colour of the deepest tint”. But this 
view does not by any means commend itself to him; for he 
continues ‘that this notion, however, is altogether incorrect, 
I venture to conclude from the following considerations :— 
“1, The progeny of individuals, embrowned by exposure 
to the sun, is born with the original complexion, and not with 
the acquired hue of the parents.” Furthermore, he points 
out that white and black races moved respectively to 
tropical and temperate climates have retained their original 
colour for ages. The second consideration which leads him 
