HETEROMORPHOSIS 



187 



stem upon the glass remained permanently the same, 

 though the tip itself moved forward at the rate of about 

 lium. each day. The longitudinal growth must, therefore, 

 have occurred in the narrowzone lying in front of flic iicir slcni. 

 13. These experiments were made in April when the 



Aglaophenise were sex- 

 ually mature. One day I 

 observed a number of small 

 (about ^mm. long), whitish, 

 cone-shaped larvae that moved 

 over the bottom of the 

 aquarium toward the window, 

 and remained there. The 

 next morning, however, they 

 had all disappeared, so that 

 I can only suspect that these 

 organisms, which in the 

 moment of observation were 

 positively heliotropic, may 

 have been larvae of Aglao- 



O 



phenia. 



VI. HETEROMORPHOSIS IN 

 PLUMULAKIA PINNATA 



1 . I have made a series of 

 FIG. 206 experiments, similar to those 

 made upon Aglaopheuia, upon Plumularia pinnata, which in 

 form closely resembles Aglaopheuia pluma. I wish to 

 describe one of these experiments here. 



A series of stalks were cut off close to the root arid fixed 

 vertically in the sand, so that the apical ends were covered 

 by it. In individual instances, but only very rarely, a new 

 tip was immediately formed at the aboral end, so that I ob- 

 tained biapical animals similar to those of Aglaophenia 



FIG. 20a 



