SPECTRUM, HELIOTROPIC REACTIONS 



33 



The method was as follows: Different stems of Eudendrium 

 with young polyps (prepared in the way described above) were 

 put successively into the same limited part of the spectrum. 

 Each stem was exposed a different length of time. The purpose 

 was to find out how much time was required to cause the maxi- 

 mum number of polyps to bend toward the light (table 8). 



TABLE 8 



Experiment 7: Eudendrium exposed to light 

 of 4700 I.u. (blue) 



The experiments show that an exposure of more than ten 

 minutes (for the light intensity used in our experiments) did not 

 essentially increase the percentage of polyps bending to the light. 



TABLE 9 

 Eudendrium exposed to light five and a half hours 



We made with the same material an experiment in which the 

 polyps were exposed for five and a half hours to the spectrum 

 from blue to red with the result shown in table 9. 



The experiment shows again, first, that even in five and a half 

 hours the rays from yellow to red are without any heliotrQpic 

 effect. Second, that the efficiency of rays with wave length of 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 19, NO. 1 



