modifications in the shape of the fruit. In animals, too, you may
produce analogous changes in this way, as in the case of that deep
bronze colour which persons rarely lose after having passed any length
of time in tropical countries. You may also alter the development of
the muscles very much, by dint of training; all the world knows that
exercise has a great effect in this way; we always expect to find the
arm of a blacksmith hard and wiry, and possessing a large development
of the brachial muscles. No doubt training, which is one of the forms
of external conditions, converts what are originally only instructions,
teachings, into habits, or, in other words, into organizations, to a
great extent; but this second cause of variation cannot be considered
to be by any means a large one. The third cause that I have to mention,
however, is a very extensive one. It is one that, for want of a better
name, has been called "spontaneous variation;" which means that when
we do not know anything about the cause of phenomena, we call it
spontaneous. In the orderly chain of causes and effects in this world,
there are very few things of which it can be said with truth that they
are spontaneous. Certainly not in these physical matters,--in
these there is nothing of the kind,--everything depends on previous
conditions. But when we cannot trace the cause of phenomena, we call
them spontaneous.

Of these variations, multitudinous as they are, but little is known with
perfect accuracy. I will mention to you some two or three cases, because
they are very remarkable in themselves, and also because I shall want to
use them afterwards. Reaumur, a famous French naturalist, a great
many years ago, in an essay which he wrote upon the art of hatching
chickens,--which was indeed a very curious essay,--had occasion to speak
of variations and monstrosities. One very remarkable case had come under
his notice of a variation in the form of a human member, in the person
of a Maltese, of the name of Gratio Kelleia, who was born with six
fingers upon each hand, and the like number of toes to each of his feet.
That was a case of spontaneous variation. Nobody knows why he was born
with that number of fingers and toes, and as we don't know, we call it a
case of "spontaneous" variation. There is another remarkable case also.
I select these, because they happen to have been observed and noted very
carefully at the time. It frequently happens that a variation occ