194 



STUDIES IN GENERAL PHYSIOLOGY 



apical and b the basal end (root), ab is suspended ver- 

 tically in the aquarium so that both cut ends are surrounded 

 by water; a is directed upward, b downward. Complete 

 regeneration occurs, a new stem S being formed at a, while 

 one or more roots W are formed at b; the former grows 



upward, the latter down- 

 ward. 



We repeat the same 

 experiment with another 

 piece of stem, only this 

 time the basal end b is 

 directed upward, while the 

 apical end a is directed 

 downward. A stem S is 

 formed at the basal end 

 which is directed upward, 

 while one or more entirely 

 normal and growing roots 

 are formed at the apical 

 end which is directed 

 downward (Fig. 43). Deli- 

 cate lateral branches spring from the new stem which are 

 directed slightly upward and carry polyps upon their upper 

 surfaces. The new branch is an image of the old. In this 

 way a heteromorphosis is readily brought about in Antennu- 

 laria. 



4. If a piece of the stem of Antennularia is suspended, 

 not vertically, but obliquely, in the aquarium (Fig. 44), a 

 stem S which grows vertically upward arises from the upper 

 cut end ; from the lower end b spring roots which grow verti- 

 cally downward; it matters not whether b is the apical or 

 the basal cut end. Thus far this experiment shows nothing 

 new. But branches ^ and S-^, and roots Wi and W ii5 may 

 arise from any other element of a stem put obliquely. The 



FIG. 44 



