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. Not a 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 31 I 

 replaced the red glass by blue. On September 11 the first 

 new polyps began to form, whose number from now on 

 steadily increased. 



