Experimental Production of Supernumerary Fore Limbs in Triturus tæniatus

Abstract

During experiments designed for a purpose remote from the subject of this communication, we had tried to remove from a young neurula of Triturus tæniatus the fore part of the presumptive area of the spinal cord and to replace it by epiblast taken from the flank of a germ of the same age. As the presumptive notochord adheres rather firmly to the overlapping neurectoblast, both were torn away together in two experiments of this series. In spite of this accident, we decided nevertheless to cover the wound by epiblast of a donor's flank. To our surprise, two symmetrical protuberances looking like fore-limb buds appeared soon after at the place which had been interfered with. They gradually developed into normally shaped supernumerary limbs conjointly with the normal fore legs.