Various other anomalies in man, more or less analogous to the foregoing,
have been advanced by different authors, as cases of reversion; but these
seem not a little doubtful, for we have to descend extremely low in the
mammalian series, before we find such structures normally present. (41. A
whole series of cases is given by Isidore Geoffroy St.-Hilaire, 'Hist. des
Anomalies,' tom, iii, p. 437. A reviewer ('Journal 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 canine character, as Owen (42. 'Anatomy of
Vertebrates,' vol. iii. 1868, p. 323.) remarks, "is indicated by the
conical form of the crown, which terminates in an obtuse point, is convex
outward and flat or sub-concave within, at the base of which surface there
is a feeble prominence. The conical form is best expressed in the Melanian
races, especially the Australian. The canine is more deeply implanted, and
by a stronger fang than the incisors." Nevertheless, this tooth no longer
serves man as a special weapon for tearing his enemies or prey; it may,
therefore, as far as its proper function is concerned, be considered as
rudimentary. In every large collection of human skulls some may be found,