The Descent of Man

their own thighs, keeping them there until the
tadpoles are born;—that certain male birds undertake
the whole duty of incubation, and that
male pigeons, as well as the females, feed their
nestlings with a secretion from their crops. But
the above suggestion first occurred to me from
mammary glands of male mammals being so
much more perfectly developed than the rudiments
of the other accessory reproductive
parts, which are found in the one sex though
proper to the other. The mammary glands and
nipples, as they exist in male mammals, can
indeed hardly be called rudimentary; they are
merely not fully developed, and not functionally
active. They are sympathetically affected
under the influence of certain diseases, like the
same organs in the female. They often secrete a
few drops of milk at birth and at puberty: this
latter fact occurred in the curious case, before
referred to, where a young man possessed two
pairs of mammae. In man and some other male
mammals these organs have been known occa-