METAMORPHOSIS OF AMPHIBIAN ORGANS 



263 



spots of the host, but later on disappeared entirely. In this 

 case, however, it was impossible to decide whether or not this 

 was due to the graft being a spotless piece of skin as this graft 

 soon after metamorphosis assumed a pathological appearance; 

 it became grayish and edematous and was gradually replaced 

 by the surrounding skin of the host. Therefore the develop- 

 ment of the spots in none of the experiments of this pair can be 

 used in studying the problems of metamorphosis. 



In experiments 43-44, the grafts developed the network inde- 

 pendently from each other and simultaneously with their re- 



spective hosts, 43 forming the network of host and graft eight 

 days before host and graft of 44. Both grafts finally became 

 spotless, since the spots developed in the beginning disappeared 

 later on. But these temporary spots were developed in both 

 grafts at the same time as the spots of the respective hosts, in 

 experiment 43, twenty-three days later than in experiment 44. 

 Experiments 27-28 are perfectly conclusive in regard to the 

 development of the network, which was formed by both grafts 

 simultaneously with their respective hosts, but appeared in host 



