THE INFLUENCE OF LIGHT ON ORGANS 429 
On August 14 over fifty polyps had developed in the 
vessel which was exposed to light, while in the vessel kept 
in the dark not a single polyp had been formed. The 
experiment was continued until September 1; the polyps 
thrived and increased in number in the light, while in the 
dark not a single polyp had yet been formed. The stems 
which up to this time had been in the dark were now 
exposed to the light. On September 6—that is to say, in 
five days—several polyps developed on each stem. The 
number of polyps increased from day to day. The same 
stems, which in three weeks had been unable to form a 
single polyp in the dark, developed a great number of them 
in five days when exposed to the light. The control ani- 
mals in the light had developed polyps from the first. 
Experiment 2.—On August 16 the stems of a new colony 
were divided equally among three vessels, two of which were 
placed in the dark and one in the light. As usual, numerous 
polyps were formed in the light in the course of five days; 
no polyps were formed at first in the dark. This experi- 
ment was also continued until September 1. By that time 
no polyps had yet developed on the stems kept in one of the 
darkened vessels; two stems in the other darkened vessel had 
developed six polyps. The animals were then exposed to 
light; in five days all the stems had produced new polyps. 
Experiment 3.—On August 25 one half of a Eudendrium 
colony was placed in diffuse light, while the other half was 
put in the dark. On September 1 a large number of polyps 
had been developed in the light; but in the dark only roots 
and no polyps had been developed. Conditions remained 
the same until September 5, when the animals which had 
been kept in the dark were exposed to the light. On the 
following day they were accidentally killed. 
These experiments show that light favors the develop- 
ment of polyps in Eudendrium; that no polyps, or only very 
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