ORGANIZATION AND GROWTH 249 
XV. SOME CASUISTIC REMARKS ON HETEROMORPHOSIS 
1. It was my intention to analyze the conditions under- 
lying heteromorphosis in other forms as carefully as I have 
done in the case of Tubularia and Antennularia. Lack of 
time, however, rendered this impossible, so I was compelled 
to postpone these experiments. I wish, however, to adda 
few casual observations. 
During the winter of 1889-90 I had already observed that 
in the aquarium the stems of Gonothyrea often grew into 
roots even when not injured externally. I thought at the 
time that lack of light and oxygen lay at the basis of these 
phenomena, but did not mention this fact, as I wished to 
make it the starting-point of new experiments. For the 
reasons given above, I did not succeed in mastering organi- 
zation in this animal in the time at my disposal, and so 
have again postponed further work upon these experiments. 
I have already called attention to the tendril-like bend- 
ings of the roots of Aglaophenia pluma in paper iv. These 
curvatures, dependent apparently upon internal causes, play 
perhaps a much more important réle than I at first antici- 
pated. They probably are responsible for the fact that the 
orientation of the organs, even those at a distance, does not 
occur with the same regularity as in Antennularia. My 
first experiments were made in very intense light, and it is 
possible that this is the determining factor in bringing 
about the downward growth of the adventitious roots in 
Aglaophenia. Considering the complexity of the conditions 
determining organization, experiments upon this animal 
with the klinostat might prove fruitful. 
I found in Sertularia that new growths which had the 
form of roots, but were positively heliotropic, formed a polyp 
at their tips after they had attained a certain length, and 
then remained positively heliotropic. According to Sachs, 
certain substances are not only necessary in the formation of 
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