TENTH LECTURE. 



SOME PROBLEMS OF REGENERATION. 



T. H. MORGAN. 



THE experiments made by Trembley, in 1740, on the regen- 

 eration of Hydra excited amongst his contemporaries the live- 

 liest interest. Curiously enough, Trembley's experiments were 

 made in order to discover whether the new creature that he 

 had found was an animal or a plant, for at that time it was 

 well known that pieces cut from a plant would give rise to new 

 plants. Trembley says : " I thought once more that perhaps 

 these organized bodies that I had observed might be plants, and 

 I had the good fortune not to reject this idea. I say that I had 

 the good fortune not to reject this idea because, although the 

 less natural one, it led me to cut up some of the polyps. I 

 judged that if the two parts of one polyp should live after being 

 separated and become each a perfect polyp, it would be evident 

 that this organized body was a plant. Yet, since I was much 

 more inclined to believe that it was an animal, I did not count 

 much on this experiment. I expected to see the polyps die." 



Reaumur had some time before shown that plant-lice could, 

 if they were isolated, multiply without sexual union, and Bonnet, 

 in 1740, convinced himself of the same fact, and Lyonet also 

 in the same year. These discoveries, Trembley said, sufficed 

 to show that in regard to the property of multiplying without 

 sexual union there is no difference between plants and animals. 1 



Trembley's results on Hydra led to the cutting up of count- 



1 Je sentois vivement que la Nature etoit trop vaste et trop peu connue pour 

 qu'on put decider sans temerite que telle ou telle propriete ne se trouvoit pas dans 

 telle ou telle classe de corps organises. 



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