"'7th. Absence of two toes out of the three of the hind leg, and
sometimes of the three, in animals whose parents had eaten up their hind-
leg toes which had become anaesthetic from a section of the sciatic nerve
alone, or of that nerve and also of the crural. Sometimes, instead of
complete absence of the toes, only a part of one or two or three was
missing in the young, although in the parent not only the toes but the
whole foot was absent (partly eaten off, partly destroyed by
inflammation, ulceration, or gangrene).
"'8th. Appearance of various morbid states of the skin and hair of the
neck and face in animals born of parents having had similar alterations
in the same parts, as effects of an injury to the sciatic nerve.'
"It should be especially observed that Brown-Sequard has bred during
thirty years many thousand guinea-pigs from animals which had not been
operated upon, and not one of these manifested the epileptic tendency.
Nor has he ever seen a guinea-pig born without toes, which was not the
offspring of parents which had gnawed off their own toes owing to the
sciatic nerve having been divided. Of this latter fact thirteen
instances were carefully recorded, and a greater number were seen; yet
Brown-Sequard speaks of such cases as one of the rarer forms of
inheritance. It is a still more interesting fact, 'that the sciatic
nerve in the congenitally toeless animal has inherited the power of
passing through all the different morbid states which have occurred in
one of its parents from the time of the division till after its reunion
with the peripheric end. It is not, therefore, simply the power of
performing an action which is inherited, but the power of performing a
whole series of actions, in a certain order.'
"In most of the cases of inheritance recorded by Brown-Sequard only one
of the two parents had been operated upon and was affected. He concludes
by expressing his belief that 'what is transmitted is the morbid state of
the nervous system,' due to the operation performed on the parents."
Mr. Darwin proceeds to give other instances of inherited effects of
mutilations:--
"With the horse there seems hardly a doubt that exostoses on the legs,
caused by too much travelling on hard roads, are inherited. Blumenbach
records the case of a man who had his little finger on the right hand
almost cut off, and which in consequence grew crooked, and his sons had
the same finger on the same hand similarly crooked. A soldier, fifteen
years before his marriage, lost his left eye from purulent ophthalmia,
and his two sons were microphthalmic on the same side."
Public-domain text, read in full here on John Shaqi.
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