The Descent of Man

nal of Anatomy and Physiology,' 1871, p. 366)
blames me much for not having discussed the
numerous cases, which have been recorded, of
various parts arrested in their development. He
says that, according to my theory, "every transient
condition of an organ, during its development,
is not only a means to an end, but once
was an end in itself." This does not seem to me
necessarily to hold good. Why should not
variations occur during an early period of development,
having no relation to reversion; yet
such variations might be preserved and accumulated,
if in any way serviceable, for instance,
in shortening and simplifying the course of
development? And again, why should not injurious
abnormalities, such as atrophied or hypertrophied
parts, which have no relation to a
former state of existence, occur at an early period,
as well as during maturity?)
In man, the canine teeth are perfectly efficient
instruments for mastication. But their true ca-