Zoology. 433 
The same characters must then be transmitted from generation to gen- 
eration. 
Cireumsiances being permanent, species are so likewise 
(5.) “hrs: however, the permanence, the fixity a are not absolute. 
The gradual expansion of a species on the surface of the globe is, at 
length, the necessary erg asa of the multiplication of individuals. 
Other causes, of an order less general may also bring about partial dis- 
placements. Whenes, especially at the limits of the “geographical distri- 
bution of the species most extended, arise notable differences of habitat 
and climate, which, in their turn lead inevitably to secondary differences 
of regimen and even of habits. To these various kinds of differences 
correspond races characterized by modifications in color and other exterior 
characteristics, in proportion and form, and sometimes even in internal 
organization. 
(These races have been arbitrarily considered, sometimes as local vari- 
eties, sometimes as distinct species 
mong domestic animals, the causes re rb are much mo 
numer us and more potent. In a long se of experiments which, 
though iudeiion with a merely seaeici sbjeehy have no arpa 
retic importance, oe of various classes, to the number of shout 
forty, have been constrained, by the intervention of man, to quit sav- 
age life, and bend t ofeany different habits, regimen and ali mates. The 
effects obtained have been in proportion to the causes; there have been 
formed a multitude of very distinct races; amon t them ebb offer 
characters equal in value to those by whi ch wih are commonly dif- 
ferentiated 
(7.) The return of many of the domestic races to the wild —— 
has taken place on various — of the globe: thence, a d series 
er 
tions, resume the characters of the latter. They only assume analogous 
characters if they are restored to savage life under conditions analogous, 
but not tehdeal 
8.) To resume: the observation of wild animals already demonstrates 
the limited pms of : species 
experiments on wild animals domesticated, and on domestic ani- 
mals returned to the wild condition, demonstrate it more clearly still. 
he same experiments prove, moreover, that the differences produced 
may be of generic value. 
9.) The truth or error of a doctrine may almost rata be brought to 
light by the value of the consequences derived from i 
The th aig of limited variability may lead to akeial solutions with 
uestions completely insoluble for the partisans of absolutely 
fixity, or atkek the i can only resolve by aid of the most complex 
and improba ble hypot 
(10.) It is thus with the ‘the fandsinental question of anthropology. ® 
ommon origin of the various human races is rationally admissible in the 
Point of view of variability, and in this point of view alone. In order to 
Am. Jour. Sct.—Sxconp Serres, Vou. XXXII, No. 96.—Nov., 1861. 
55 
