258 



EDUARD UHLENHUTH 



the host's spots after the animal was fully metamorphosed (figs. 

 7 and 8). We shall return later to this phenomenon. It is 

 more difficult to understand the origin of the orange yellow spot 

 in front of the graft of experiment 22, as the history of this 

 spot is missing. But it seems certain that this spot either be- 

 longed to the graft or was formed at least under its influence 

 and with the aid of the graft's yellow chromatophores. In 

 favor of the suggested origin of this spot is the fact that among 

 a very large number of metamorphosed animals which did not 

 have pieces of skin grafted from other individuals, such a wide 

 and very distinct difference in the color of the spots was never 

 observed. 



In experiments 41-42, the grafts developed their network simul- 

 taneously with each other, as also did the hosts, but the host and 

 graft of experiment 41 developed spots five days earlier than 

 host and graft of experiment 42. 



In experiments 25-26, the development of the network on the 

 grafts occurred simultaneously with their respective hosts, but 

 not simultaneously with each other: Hence just the opposite 

 occurred of what would be expected if the rate of development 

 of the grafts were determined by animal A, to which both grafts 

 originally belonged. In experiment 26 the first trace of the net- 

 work appeared seven days earlier than in experiment 25. In 



