Charles Robert Darwin

“ No doubt the fact of variations being sometimes inherited at an earlier age than that at which they first appeared—a form of inheritance which has been called by some naturalists "accelerated inheritance"—is almost equally important, for, as was shown in the first edition of the "Origin of Species," all the leading facts of embryology can be explained by these two forms of inheritance, combined with the fact of many variations arising at a somewhat late stage of life. ”

“ The eldest daughter began to turn gray at about twenty, and her hair at thirty was perfectly white. A second daughter began to be gray at the same age, and her hair is now almost white. The two remaining daughters have not inherited the peculiarity. Two of the maternal aunts of the father of these children "began to turn gray at an early age, so that by middle life their hair was white." ”

“ Bishop has also given me a case of inheritance of another kind, namely, of a peculiarity which arose, as it appears, from an injury, accompanied by a diseased state of the part. This latter fact seems to be an important element in all such cases, as I have elsewhere endeavored to show. A gentleman, when a boy, had the skin of both thumbs badly cracked from exposure to cold, combined with some skin-disease. His thumbs swelled greatly, and remained in this state for a long time. ”