THe INFLUENCE OF LIGHT ON ORGANS 431 
increased, but not a single one was formed in the red light. 
On September 8, seventy new polyps with stems 3-10 mm. 
long had developed in the blue light. Nota single polyp 
had developed in the red light, but a few roots had been 
formed. Conditions did not change during the following 
days. After nine days not a single polyp had developed in 
the red light, while over seventy thriving polyps had been 
‘formed in the blue light. 
In order to test whether the stems in the red light would 
develop polyps if brought into the blue light, I substituted 
a blue glass for the red glass on September 9. Two days 
later, on September 11, indications of new polyps were 
already apparent, and on the following day thirty-two com- 
plete polyps had been formed; on the next day the number 
had increased to sixty-six. From these experiments it is 
seen that in the development of polyps red light acts more 
like darkness, while blue light acts like mixed daylight, just 
as in heliotropic phenomena. 
Experiment 2.—On August 22 a large number of stems 
of Eudendrium were equally divided, as in the preceding 
experiments, between two vessels, one of which was placed 
in blue, the other in red light. After the old polyps had 
fallen off, the first new polyps appeared in the blue light on 
August 27. At about the same time roots began to develop 
in the red light, but no polyps. On August 29 forty vigor- 
ously growing polyps had developed in the blue light, while 
in the red light no polyps but only roots had developed. On 
August 31 the culture in the blue light had formed a forest 
of new, well-developed polyps, while the culture in the red 
light had only developed several roots. The culture in the 
blue light had also developed a few roots. On August 311 
replaced the red glass by blue. On September 11 the first 
new polyps began to form, whose number from now on 
steadily increased. 
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