EVOLUTIONARY VIEWS OF BUFFON 205 
cepted, to alterations, changes, and variations of all 
kinds. Being free to choose their own food and cli- 
mate, they vary less than domestic animals vary.” * 
The Buffonian factor of the direct influence of 
climate is not in general of so thoroughgoing a char- 
acter as usually supposed by the commentators of 
Buffon. He generally applies it to the superficial 
changes, such as the increase or decrease in the 
amount of hair, or similar modifications not usually 
regarded as specific characters. The modifications 
due to the direct influence of climate may be effected, 
he says, within even a few generations. 
Under the head of geographical distribution (in 
tome ix., 1761), in which subject Buffon made his 
most original contribution to exact biology, he claims 
to have been the first “even to have suspected ” that 
not a single tropical species is common to both 
eastern and western continents, but that the animals 
common to both continents are those adapted toa tem- 
perate or cold climate. He even anticipates the sub- 
ject of migration in past geological times by supposing 
that those forms travelled from the Old World either 
over some land still unknown, or “more probably” 
over territory which has long since been submerged.t 
The mammoth “was certainly the greatest and 
strongest of all quadrupeds, but it has disappeared ; 
and if so, how many smaller, feebler, and less re- 
markable species must have perished without leaving 
us any traces or even hints of their having existed ? 
How many other species have changed their nature, 
* Tome vi., pp. 59-60 (1756). + Butler, 7 ¢., pp. 145-146. 
