1765, Spalanjani began to study the ability of animal regeneration. He has done thousands of experiments with earthworms and realized the exact location of some incisions that are conducive to earthworm regeneration. After studying the tentacles of slugs, the head, tentacles and feet of snails, the tail, limbs and maxilla of salamanders, and the limbs of frogs and toads, he found that animals have stronger regeneration ability than higher animals, larvae are stronger than adults, and body surface tissues are stronger than internal organs. In addition, he also made a successful allogeneic head transplantation experiment with snails. He collected his research results in two books, namely Animal Regeneration and Experimental Results of Head Regeneration of Land Snails.