nd in about three
months' time the stump was removed for the second time by the root. But
it has since grown again, and is now fully a third of an inch in
length, including a bone; so that it will for the third time have to be
operated on.

Now the normal digits in adult man and other mammals, in birds, and, as
I believe, in true reptiles, have no power of regrowth. The nearest
approach to this power is exhibited by the occasional reappearance in
man of imperfect nails on the stumps of his fingers after
amputation.[33] But man in his embryonic condition has a considerable
power of reproduction, for Sir J. Simpson[34] has several times
observed arms which had been cut off in the womb by bands of false
membrane, and which had grown again to a certain extent. In one
instance, the extremity was "divided into three minute nodules, on two
of which small points of nails could be detected;" so that these
nodules clearly represented fingers in process of regrowth. When,
however, we descend to the lower vertebrate classes, which are
generally looked at as representing the higher classes in their
embryonic condition, we find ample powers of regrowth. Spallanzani[35]
cut off the legs and tail of a salamander six times, and Bonnet eight
times, successively, and they were reproduced. An additional digit
beyond the proper number was occasionally formed after Bonnet had cut
off or had divided longitudinally the hand or foot, and in one instance
three additional digits were thus formed.[36] These latter cases appear
at first sight quite distinct from the congenital production of
additional digits in the higher animals; but theoretically, as we shall
see in a future chapter, they probably present no real difference. The
larvae or tadpoles of the tailless Batrachians, but not the adults,[37]
are capable of reproducing lost members.[38] Lastly, as I have been
informed by Mr. J. J. Briggs and Mr. F. Buckland, when portions of the
pectoral and tail fins of various {16} fresh-water fish are cut off,
they are perfectly reproduced in about six weeks' time.

From these several facts we may infer that supernumerary digits in man
retain to a certain extent an embryonic condition, and that they resemble
in this respect the normal digits and limbs in the lower vertebrate
classes. They also resemble the digits of some of the low