METAMORPHOSIS OF AMPHIBIAN ORGANS 253 



In experiment 6 the yellow network of the host had formed on 

 September 11, while on graft no network ever was developed. 

 The animal was set on land-condition on September 23 and 

 October 9 the network of the host had separated into greenish 

 spots and simultaneously on graft two yellowish spots had come 

 out. 



In experiment 7 the yellow network of the host appeared on 

 August 28, while on graft there was never any network formed. 

 On August 30 the network of the host was already separated 

 into greenish and yellowish spots and on graft, 5 small spots had 

 formed; the animal was transferred to land-condition the same 

 day. On September 5 host and graft were already very dark and 

 cleared up gradually until they were finally black and their 

 spots bright yellow. 



In experiment 13 the host was one of those animals which 

 for some reason do not develop any spots at all on the back or 

 form only after a long time a few faint and small greenish spots, 

 consisting of very loose, tiny greenish or yellowish pigment dots. 

 For this reason this experiment appears to be of very little value 

 in connection with the problem of metamorphosis. Since we 

 will have to come back to this experiment when other problems 

 will be at issue, it may be briefly outlined here. 



On August 28 the graft had developed two light yellow spots, 

 while the host showed only a very faint greenish pigmentation 

 spread over the yellow brown background. After the animal 

 was set on land-condition (September 1), host and graft turned 

 darker and darker, but while the graft still had two large green- 

 ish spots, the host had remained in the network stage and its 

 network was of such a faint and indefinite character that it 

 could not be traced • exactly nor ascertained whether or not it 

 was isolated. The spots of the graft turned bright yellow on 

 September 11 while on the host's body the first greenish spots 

 were not recognized before September 18 and did not become 

 distinct before September 23 (three weeks after the animal 

 had left the water). The body of the host never developed 

 more than a few small greenish dotted spots, but turned black 

 simultaneously with the graft, whose spot finally disappeared. 



