No. 43»-] AMBLYSTOMA TIGRINUM. 405 



completer stages being such as began slowly, after at least 

 several days of contented life below water. 



Before leaving these experiments, I will note that, in spite of 

 their fatal results and the convincing testimony they bear to the 

 inability of these organisms to make complete adaptive response 



this case an attempt to retain the branchiate condition. For 

 when the fatal resorption of tissues began, the gills were not, as 

 is usually the case, one of the first organs to be attacked. In 

 some instances they showed no diminution in size or function 

 for several days after the back fin was greatly reduced. Such 



they are not frequent, and may perhaps, in all cases indicate 

 that a high functional activity of the branchiae is for a time 

 holding in check the katabolic changes which are elsewhere set- 

 ting in. Similar observations may be made on the occasional 

 overgrown, giant larvae, in which the branchial apparatus seems 

 frequently to resist metamorphic processes until other parts of 

 the organism are well under way in the change. 



A fairly complete resume has now been presented of the 

 classes of facts which seem to indicate that the metamorphosis 

 of Amblystoma, if not of all tailed amphibia, has heretofore 



queries that nam rally 



