and that we are his descendants--suppose that this had ever happened,
and that the first residence of this human being was on the West Coast
of Africa. There is no great structural difference between the white
man and the Negro, and yet there is something so singularly different
in the constitution of the two, that the malarias of that country, which
do not hurt the black at all, cut off and destroy the white. Then you
see there would have been a selective operation performed; if the white
man had risen in that way, he would have been selected out and removed
by means of the malaria. Now there really is a very curious case of
selection of this sort among pigs, and it is a case of selection of
colour too. In the woods of Florida there are a great many pigs, and
it is a very curious thing that they are all black, every one of them.
Professor Wyman was there some years ago, and on noticing no pigs but
these black ones, he asked some of the people how it was that they had
no white pigs, and the reply was that in the woods of Florida there was
a root which they called the Paint Root, and that if the white pigs
were to eat any of it, it had the effect of making their hoofs crack,
and they died, but if the black pigs eat any of it, it did not hurt
them at all. Here was a very simple case of natural selection. A
skilful breeder could not more carefully develope the black breed of
pigs, and weed out all the white pigs, than the Paint Root does.

To show you how remarkably indirect may be such natural selective
agencies as I have referred to, I will conclude by noticing a case
mentioned by Mr. Darwin, and which is certainly one of the most curious
of its kind. It is that of the Humble Bee. It has been noticed that
there are a great many more humble bees in the neighbourhood of towns,
than out in the open country; and the explanation of the matter is
this: the humble bees build nests, in which they store their honey and
deposit the larvae and eggs. The field mice are amazingly fond of the