Professor Romanes fully acknowledges that there is the "gravest possible doubt" as to the transmission of the effects of disuse (Letter on Panmixia, _Nature_, March 13, 1890). [52] _Variation of Animals and Plants under Domestication_, ii. 287-289. [53] _Descent of Man_, pp. 612, 131. INHERITED INJURIES. INHERITED MUTILATIONS. The almost universal _non-inheritance_ of mutilations seems to me a far more valid argument _against_ a general law of modification-inheritance than the few doubtful or abnormal cases of such inheritance can furnish in its favour. No inherited effect has been produced by the docking of horses' tails for many generations, or by a well-known mutilation which has been practised by the Hebrew race from time immemorial. As lost or mutilated parts are reproduced in offspring independently of the existence of those parts in the parent, there is the less reason to suppose that the particular condition of parental parts transmits itself, or tends to transmit itself, to the offspring. So unsatisfactory is the argument derivable from inherited mutilations that Mr. Spencer does not mention them at all, and Darwin has to attribute them to a special cause which is independent of any general theory of use-inheritance.[54] Darwin's most striking case--and to my mind the only case of any importance--is that of Brown-Sequard's epileptic guinea-pigs, which inherited the mutilated condition of parents who had gnawed off their own gangrenous toes when anaesthetic through the sciatic nerve having been divided.[55] Darwin also mentions a cow that lost a horn by accident, followed by suppuration, and subsequently produced three calves which had on the same side of the head, instead of a horn, a bony lump attached merely to the skin. Such cases may seem to prove that mutilation _associated with morbid action_ is occasionally inherited or repeated with a promptitude and thoroughness that contrast most strikingly with the imperceptible nature of the immediate inheritance of the effects of use and disuse; but they by no means prove that mutilation in general is inheritable, and they are absolutely no proof whatever of a _normal_ and non-pathological tendency to the inheritance of acquired characters. Those who accept Darwin's special explanation of the supposed inheritance of mutilations, ought to notice that his explanation applies equally well under a theory which is strongly adverse to use-inheritance--namely, Galton's idea of the sterilization and complete "using up" of otherwise reproductive matter in the growth and maintenance of the personal structure.