198 STUDIES IN GENERAL PHYSIOLOGY 



roots. Several of the branches on the upper surface in the 

 neighborhood of the growing stem cd have also become 

 roots, but this is an exception which we shall discuss later. 



2. I cut some long pieces from the stem of an Antennula- 

 rian, bout them, and hung them into the aquarium, as shown 

 in Figs. 4."), 4(5. 47. Both ends were oriented in the same way 

 toward the center of the earth. After some time (Fig. 4tJ) 

 the branches of the under surface of the nearly horizontal 

 piece ab began to grow as roots. Some time later the same 

 occurred in all those branches, the tips of which were 

 directed downward. In Fig. 47 is shown a second specimen 

 of the same series of experiments, but drawn six week later. 

 All the branches from a to b, the tips of which were directed 

 downward, have grown into roots. By carefully studying 

 Fig. 45 this phenomenon can again be observed; only I 

 must call attention to the fact that this drawing was made 

 very shortly after the beginning of the experiment, and that the 

 formation of roots had consequently not progressed very far. 



Macroscopic-ally the course of the heteromorphosis of a 

 branch is as follows: The tip of the branch situated upon the 

 lower side of the stem dies, and the polyps and nematophores 

 disappear. The new root then sprouts from the free distal end 

 of the branch, without any operative injury whatsoever hav- 

 ing been inflicted upon the branch. 



3. While I always succeeded under the conditions de- 

 scribed above, in causing the lateral branches to grow into 

 roots, I succeeded only once in making them grow into a 

 stem. This is shown in Fig. 48. A short piece ab of an 

 Antennularian stem was laid horizontally in the water. 

 After eorne time the tip of one of the lateral branches c 

 began to grow vertically upward. No new lateral branches 

 were formed upon it. A similar negatively geotropic new 

 growth arose from the aboral cut end at a. 



4. The heteromorphoses possible through changes in the 



