With respect to the inheritance of structures mutilated by injuries or altered by disease it is difficult to come to any { 23} definite conclusion. In some cases mutilations have been practised for a vast number of generations without any inherited result. Godron has remarked[60] that different races of man have from time immemorial knocked out their upper incisors, cut off joints of their fingers, made holes of immense size through the lobes of their ears or through their nostrils, made deep gashes in various parts of their bodies, and there is no reason whatever to suppose that these mutilations have ever been inherited. Adhesions due to inflammation and pits from the small-pox (and formerly many consecutive generations must have been thus pitted) are not inherited. With respect to Jews, I have been assured by three medical men of the Jewish faith that circumcision, which has been practised for so many ages, has produced no inherited effect; Blumenbach, on the other hand, asserts[61] that in Germany Jews are often born in a condition rendering circumcision difficult, so that a name is here applied to them signifying "born circumcised." The oak and other trees must have borne galls from primeval times, yet they do not produce inherited excrescences; many other such facts could be adduced.
On the other hand, various cases have been recorded of cats, dogs, and horses, which have had their tails, legs, &c., amputated or injured, producing offspring with the same parts ill-formed; but as it is not at all rare for similar malformations to appear spontaneously, all such cases may be due to mere coincidence. Nevertheless, Dr. Prosper Lucas has given, on good authorities, such a long list of inherited injuries, that it is difficult not to believe in them. Thus, a cow that had lost a horn from an accident with consequent suppuration, produced three calves which were hornless on the same side of the head. With the horse, there seems hardly a doubt that bony 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 { 24} two sons were microphthalmic on the same side.[62] In all such cases, if truthfully reported, in which the parent has had an organ injured on one side, and more than one child has been born with the same organ affected on the same side, the chances against mere coincidence are enormous. But perhaps the most remarkable and trustworthy fact is that given by Dr. Brown-Séquard,[63] namely, that many young guinea-pigs inherited an epileptic tendency from parents which had been subjected to a particular operation, inducing in the course of a few weeks a convulsive disease like epilepsy: and it should be especially noted that this eminent physiologist bred a large number of guinea-pigs from animals which had not been operated on, and not one of these manifested the epileptic tendency. On the whole, we can hardly avoid admitting, that injuries and mutilations, especially when followed by disease, or perhaps exclusively when thus followed, are occasionally inherited.