THE AXIAL GRADIENTS IN HYDROZOA. 



187 



resorbed and extensive stolon systems developed from practically 

 all tips (Fig. 10). These stolons bear a few erect stems with 

 hydranth buds (Fig. 10; h, h}, but these did not develop further. 



11. In HC1 W/5OOO pH 7.4, after forty-eight hours, most 

 terminal hydranths of upper branches disintegrated and many 

 subapical stolons present. Many hydranths at lower levels 

 intact ; no stolons. In controls in sea water, changed daily, termi- 

 nal hydranths mostly disintegrated but new hydranths develop- 

 ing and very few stolons present. 



12. In HC1 m/i5OO pH 6.9 hydranths disintegrate in one to 

 two days, terminal hydranths usually first. After three days 

 numerous stolons appeared in basal halves of pieces, but all 

 development was inhibited in the apical halves. In sea water 

 controls after three days the original hydranths were gone, many 

 new hydranths were developing and few stolons appeared. 



13. In pieces kept in standing water in closed vessels without 

 air the changes during the first forty-eight hours are essentially 



