200 



STUDIES T\ GENERAL PHYSIOLOGY 



FIG. 50 



From the lower apical end sprang the downward- 

 growing roots W, which remained much shorter 

 than the roots W l . A complete heteromor- 

 phosis had therefore been produced, a 

 root having hern formed in place of the 

 old tip, and a stem in place of the 

 root. I now turned the whole animal 

 about a horizontal axis through an 

 angle of nearly 180, by which 

 process the animal was placed 

 in the position shown in the 

 drawing. The arrow indi- 

 cates the direction of the 

 vertical. The tip of the 

 stem which was now 

 directed downward 

 ceased to grow, but 

 the stem retained 

 its vigor and its 

 normal appear- 

 ance. Several 

 - roots IV. 



3 ' 



its 



were formed 

 at its lower end 

 c, and, besides, 

 other roots, W 

 sprang from 

 lower surface. These 

 perhaps came in part 

 or entirely from the lateral 

 branches. The old roots 

 at a continued to live, so 

 that the animal terminated in 

 roots at both ends. 



The same series of phenomena, 

 differing only in detail, is shown in 

 Fig. 50. The stem ab was suspended 

 obliquely in the aquarium, the apical 

 end b being higher than a. The stem 

 de sprang from the surface which at that 

 time had been uppermost, and from an ele- 

 ment lying fairly low down upon the stem. 

 Roots W sprang from the point which origi- 



