TENTH LECTURE. 



COALESCENCE EXPERIMENTS UPON THE 



LEPIDOPTERA. 



HENRY E. CRAMPTON, Jr. 



The subject of animal-grafting, or the production of coales- 

 cence between individuals or parts of individuals, has recently 

 been placed among the most important of modern biological 

 problems by the admirable studies of G. Born upon the 

 embryos of amphibia. It had already been shown by the 

 work of Trembley and, more recently, of Wetzel, upon 

 Hydra, and by that of a student of Korschelt, Joest, upon 

 LjimbricidcB, that portions of two different animals could be 

 made by proper means to coalesce perfectly. Born, however, 

 was the first to make full demonstration in this regard of the 

 powerful formative energy of embryonic tissue, which is so 

 much greater than the mere regenerative capacity of adult 

 tissues. 



By carefully cutting in two frog and toad embryos at the 

 stage when the head and tail are being marked off from the 

 trunk, and by placing the wounds of the fragments in contact, 

 keeping them together by bits of silver wire laid against and 

 across them, Born was able to produce some most interest- 

 ing and almost grotesque monsters. Two tadpoles united 

 belly to belly with a common liver, a head fused to the belly 

 or back of a complete tadpole, tadpoles cut in half and halves 

 exchanged, tadpoles united head to head — these are some of 

 the unique products of Born's experiments. 



The fusion processes of the internal organs and tissues in 

 these cases are of extreme interest. Born found that when 



