178 
segregation there would have been one case of isolation, but 
after the segregation there would be five such cases. 
VaRIABILITY.—The most important and fundamental cause 
of evolution must necessarily be the innate tendency of all 
organisms to vary one from the other, for a close inspection 
reveals the fact that no two are exactly alike. It is found 
tain directions may be ifte inoperative ee applied to 
others. Romanes quotes as an example of the Eee the 
goose, which Darwin calls an “inflexible type” compared 
with most other domesticated birds. He also fedi to some 
extremely striking examples quoted by Weissmann for the 
sake of showing that there are cases which seem to tell 
against the general Bann of modification as due 
es es 
ica are habitually compelled to form small isolated colo- 
widely separated ponds, and, nevertheless, exhibit no 
Bene of character, although isolation has probably 
la 
sted for centuries Again, on Mount Kosciusko were 
found specimens of flora and fauna characteristic of the 
alpine regions a. On the other hand, the land 
me. of Maderia and the Sandwich Islands present diversi- 
es of types as numerous almost as the different sites suit- 
able for local isolation. It is evident, therefore, that the 
mus 
evolution. In the om — where ~ type is pure, 
the tendency to variability appears to be l, 
conveniently seen in cus Jewish, un and ‘ifellabeon types. 
In the case of the Australian aborıginal, whether he is 
geographical position. His type is found nowhere else, and 
he has shown but little tendency to vary that t so that 
the presumption is on the side of an autochthonous origin. 
The ee of a tendency to variability must, therefore, have 
been an important factor in pode ucing uniformity of type 
amongst the Australian aborigine 
