HETEROMORPHOSIS 



131 



the nearer the tip they are. These points enable one to dis- 

 tinguish between the basal end (originally directed toward 

 the root) and the apical end (originally directed toward the 

 tip) of a stem from which the tip and root have been cut. 

 2. I cut off some stems of Aglaophenia pluma close to the 



FIG. 17 



FIG. 19 



root, and fixed them vertically, but with their tips down- 

 ward, into the sand. The tips were planted just deeply 

 enough to keep the animals in a vertical position. The 

 remaining part of the stem was surrounded by water. In a 

 of these, (iii/n/dls new ti]>x, irliiclt roidinncd lo grow 

 , were formed at 1//c Ixixtd end* (Figs. 18, 19). At 

 first the old main stem grew in length by growing vertically 

 upward. From this there thru arose the lateral branches. 

 The new polyps which were formed grew only upon the 



