ORGANIZATION AND GrowTH 215 
only apparent. It may be that I had to do with a bifur- 
cation of a root which had been produced through contact 
stimuli, of which the one branch continued to grow without 
contact. But, as before, I did not succeed in causing the 
growth of a root at the oral pole in even a single instance; 
it may be that this is impossible in Tubularia by any of the 
means which I have employed thus far. In the light of my 
previous experiments on Antennularia and Aglaophenia, I 
need not emphasize that this is only a special characteristic 
of Tubularians. 
If a root is formed at one extremity of a Tubularian, 
and this has grown vigorously for some time, its tip not 
infrequently becomes faintly red, and this coloration deepens 
rapidly; in such cases a polyp forms at the tip of the root, 
which then immediately bends away from the substratum 
upon which the root has grown and grows almost perpendic- 
ularly upward. We then have a colony of two polyps which 
are attached to the base upon which they grow by a common 
root. The difference between such an animal and the 
heteromorphic bioral animal lies in the fact that the latter 
lacks an inherited organ, the root. In its place a polyp has 
been formed. 
VI. EXPERIMENTS ON ORGANIZATION IN CIONA INTESTINALIS 
1. The animals in which I have thus far been able to 
produce heteromorphoses stand low in the animal scale; we 
have dealt only with Hydrozoa. It might be thought that 
these “colony-forming” animals are an exception to the gen- 
eral rule, and that only in them a movement of formative 
substances can take place in both directions in the sense of 
Sachs’s theory. Such a view is supported by the fact that 
“polarity” is very pronounced in a series of Actinis, and 
that, in spite of my efforts, I have not succeeded in bringing 
about heteromorphoses in them. The fact that a solitary 
Digitized by Microsoft® 
