SPECTRAL COLOR AND STIMULATION 



501 



483.4 MM- This variation in magnitude was no doubt due to 

 slight changes in the position of the image of the filament in the 

 lamp on the sht of the spectrometer, caused largely by the bend- 

 ing of the filament in the process of heating. This contention is 

 supported by the fact that inconsistent readings in a given group 

 of tests were obtained only if during the process of making the 

 tests in the group the lamp was turned off and allowed to cool 

 and then turned on again. 



TABLE 6 

 Phacus triqueler {negative). Euglena granulata {negative). Relation between wave 



length and stimulation 



Euglena granulata 



Euglena granulata was discovered in one of the clay pools at 

 Nela Park on August 25 but not in sufficient numbers to make 

 work on it very satisfactory. Only one series of tests was made 

 on the specimens collected at this time and the species was not 

 again found during the season except here and there an isolated 

 individual. 



The results of the series of tests made may be found in table 6. 

 This series of tests indicates that the distribution of stimulating 

 efficiency in the spectrum for this species is the same as it s for 

 the three species already discussed (see table 15). 



