Further experiments on the innervation and function of grafted supernumerary limbs in the embryo of

PREVIOUS studies on the transplantation of limbs in the embryo of Eleutherodactylus martinicensis have shown that supernumerary limbs tend to be less well innervated than are corresponding replacing grafts, and that the innervation of the former, either autografts or homografts, is progressively less extensive with increase in time after operation. The degree to which grafted supernumerary forelimbs show movement in life parallels the extent of their motor innervation when studied subsequently in serial sections. The loss of innervation and of movement is particularly drastic near the time when the animal normally hatches and the tail undergoes atrophy. The present paper describes some further experiments made with the aim of throwing light on the causes which underly the degeneration of motor nerves within supernumerary limb grafts in this animal.