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. Icut some long pieces from the stem of an Antennula- 
rian, bent them, and hung them into the aquarium, as shown 
in Figs. 45, 46,47. Both ends were oriented in the same way 
toward the center of the earth. After some time (Fig. 46) 
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 
veryshortly after the beginning of the experiment,and that the 
formation of roots had consequently not progressed very far. 
Macroscopically 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. 
83. 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 some 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 
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