There are a number of old and curious observations in regard to cases of grafting in higher animals. It was found by Hunter and by Duhamel that the spur of a young cock could be grafted upon the comb, when it continued to grow to its normal size. The comb, being richly supplied with blood, furnished the nourishment for the growth of the spur. Fischer transplanted the leg of an embryo bird to the comb of a cock, or of a hen, where it grew at first, but after some months degenerated. Zahn transplanted the fœtal femur to the kidney, where it grew for a time, but later degenerated. Bert transplanted the tail of a white rat to the body of _Mus decumanus_, where it continued alive; but he found that the tail of the field mouse, _Mus sylvaticus_, did not grow so well on the rat, and the tail of a rat would not unite at all with the body of a dog or of a cat. Bert bent over the tip of the tail of a rat, and grafted the distal end into the skin of the back of the same animal. After the tip had established union with the surrounding tissues, the tail was cut off at its base. The grafted tail remained alive, but did not regenerate at its free end. There are several cases described by pathologists in which the skin of one mammal has been transplanted to another. The transplantation of the skin of the negro upon a white man has been brought about, but the evidence as to what subsequently happened is contradictory. It appears that while in many instances the transplanted skin has remained alive for a time, yet later it was thrown off by new skin growing under it and replacing it. Leo Loeb has described a curious instance of grafting pieces of skin of different colors in the guinea pig. If a piece of black skin from the ear of a guinea pig is grafted upon the white ear of another animal, it unites and continues to live, but if a piece of white skin is grafted upon a black ear, it is slowly thrown off and replaced by new black skin that has regenerated around the edge of the graft from the tissue of the black ear.