﻿i 9 i6] BOVIE— SCHUMANN RAYS 1 3 



of 10 seconds was required to kill the swarm spores. Exposures of 

 one second duration were then made at intervals of several seconds. 

 It was found that the action of the Schumann rays is additive. 

 The swarm spores were killed only when the total exposure equaled 

 10 seconds. Other organisms gave similar results. The fact that 

 the action of the light is additive made it possible to interrupt the 

 exposure from time to time, and to make a detailed study of the 

 progress of the changes produced by the light. The protoplasm of 

 the swarm spores which had been killed by the light had a granular 

 appearance. Often some of 

 the protoplasm was extruded 

 from the cells and was 

 rounded up into drops. 



The cells of a large Spiro- 

 gyra of the crassa type were 

 killed by an exposure of 45 

 seconds when the discharge 

 tube was carrying 18 milli- 

 amperes. The first visible 

 change was the disappearance 

 of the wavy margin of the 

 chlorophyll bands. This be- 

 gan on the side of the cell 

 nearest the light. Later the 

 bands broke into isolated 

 rounded drops, each drop 

 containing a pyrenoid. At the same time that the bands were 

 breaking up, they became shorter and contracted around the 

 nucleus. As they contracted, they moved away from the cell wall, 

 pulling the protoplasm lying next to the wall out into threads of 

 viscous appearance. The nucleus became swollen and distended. 



When an active amoeba was exposed to the light of the hydrogen 

 discharge tube there was a momentary cessation of motion, fol- 

 lowed by a withdrawal of the advancing pseudopodia. Locomotion 

 in another direction began again at once, before the pseudopodia 

 were entirely withdrawn. The extended pseudopodia often turned 

 directly upward away from the light of the discharge tube, and 



VV 



