no Amos W. Peters. 



The result shows that direct sunlight prevents the occurrence of 

 phosphorescence and that mechanical stimulation accelerates it. 



Experiment 2. Two phosphorescent lots, A and B, were 

 exposed to direct sunlight for three minutes. They were then 

 both placed in the dark-box at the same time. They were both 

 found to be non-phosphorescent. A was then continuously 

 agitated and B was left undisturbed except for tests, as above 

 described. A phosphoresced first in 2.5 minutes; B in 3.0 min- 

 utes. 



After permitting the phosphorescence to develop for a minute 

 or two, A was exposed to direct sunlight for two minutes while 

 B remained in diffuse daylight. A was continually agitated in 

 the dark-box as above described. A phosphoresced first in i 

 minute; B continued to phosphoresce. 



After some minutes both were exposed to diffuse daylight and 

 then tested as follows: A was agitated in the dark-box, while B 

 remained undisturbed, A first phosphoresced in i minute; B in 

 2 minutes. 



The result indicates that exposure to direct sunlight not only 

 prevents phosphorescence, as found in the preceding experiment, 

 but also overcomes a previously acquired power to phosphoresce. 

 Furthermore mechanical stimulation, as before, accelerates the 

 appearance of phosphorescence. 



Experiment 5. It was observed that Mnemiopsis was some- 

 times phosphorescent and sometimes not so after standing for a 

 time in the diffuse daylight of the laboratory. The object of this 

 experiment was to test the power of diffuse daylight, of the inten- 

 sity then prevailing in the laboratory, to inhibit or permit phos- 

 phorescence, as well as to test further the influence of mechanical 

 stimulation. The ctenophores used had been exposed to diffuse 

 daylight. A was agitated in the dark-box, but B, in the same 

 box, was undisturbed except for tests. Both A and B were then 

 again exposed to diffuse daylight. A was then put in the dark- 

 box and agitated; B was undisturbed except for tests. A phos- 

 phoresced first in 1.7 minutes; B in 2.5 minutes. 



The results show that diffuse daylight can check phosphores- 

 cence and, as before, mechanical stimulation can accelerate its 

 appearance. 



Experiment ^. In this experiment ctenophores in the dark-box 

 were continuously agitated with a glass rod to determine whether 



