CHAPTER I 

 GENERAL INTRODUCTION 



ALTHOUGH a few cases of regeneration were spoken of by Aris- 

 totle and by Pliny, the subject first attracted general attention 

 through the remarkable observations and experiments of the Abb 

 Trembley. His interest was drawn to certain fresh-water polyps, 

 hydras, that were new to him, and in order to find out if the organisms 

 were plants or animals he tried the effect of cutting them into pieces ; 

 for it was generally known that pieces of a plant made a new plant, 

 but if an animal were cut into pieces, the pieces died. Trembley found 

 that the polyp, if cut in two, produced two polyps. Logically, he 

 should have concluded that the new form was a plant ; but from 

 other observations, as to its method of feeding and of movement, 

 Trembley concluded that the polyp was an animal, and that the 

 property of developing a new organism from a part must belong to 

 animals as well as to plants. " I felt," he says, " strongly that nature 

 is too vast, and too little known, for us to decide without temerity 

 that this or that property is not found in one or another class of 

 organized bodies." 



Trembley's first experiments were made in 1740, and the remark- 

 able results were communicated by letter to several other naturalists. 

 It came about in this way that before Trembley's memoir had 

 appeared, in 1744, his results were generally known, and several 

 other observers had repeated his experiments, and extended them 

 to other forms, and had even published an account of their own 

 experiments, recognizing Trembley, however, as the first discoverer. 

 Thus Reaumur described, in 1742, a number of other forms in which 

 regeneration takes place; and Bonnet, in 1745, also described some 

 experiments that he had made during the four preceding years. 

 Widespread interest was aroused by these results, and many different 

 kinds of animals were experimented with to test their power of 

 regeneration. Most important of these new discoveries were those 

 of Spallanzani, who published a short preliminary statement of his 

 results, in 1768, in his Prodrome. 



