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