Spallanzani[95] was the first to study the regeneration of the limb in salamanders, and found that the skeleton in the new part is like that in the normal limb. Bonnet, Philipeaux,[96] as well as other naturalists,[97] also examined the regeneration of the limbs of salamanders. Götte (’79) has studied the embryonic development and the regeneration of the limb of triton, especially in regard to the origin of the new bones. He found that the skeleton develops in much the same way in the embryonic limb and in the regenerated limb, and the process in the latter may be said to repeat that in the former. This is especially true for the regeneration of the limb of a very young larva, but the older the larva the more it departs from the embryonic type of development. If the limb is cut off through the upper arm, or through the thigh, new tissue develops over the cut-end. If the larva is quite young, so that formation of the cartilages in the leg has not gone very far, the new tissue differs very little from the old; but if the leg of an older larva is amputated, the difference between the old and the new parts is more striking. If the bones of the leg have become ossified, the transition from the old to the new part is at first very sharp. The new tissue, that will make the new cartilages of the new limb, develops as a cap over the cut-end of the old bone. Götte does not give an explicit statement in regard to the origin of the new cartilage, but his account leads one to suppose that it develops from the old cartilage or from some part of the bone. This is, in fact, the case, as I have observed in preparations of the regenerating leg of _Plethodon cinereus_, in which the new cartilaginous tissue comes from the periosteum of the old bone. Götte shows that two long rods of tissue are formed, that are separate for the greater part of their length. They give rise to the two bones of the lower leg, or forearm, as the case may be. The broken end of the femur or humerus also completes itself by a short cartilaginous cap, which is at first continuous with the two rods just described. The ends of these two rods break up into a series of pieces that form the tarsalia, or the carpalia, and the digits. Two digits are first formed, and the others are added as outgrowths from the side of one of the two rods. It is important to note that the new cartilages are formed, in large part, out of a continuous substratum (or rather of two) which separates into proportionate parts to produce the elements of the new limb.