150 BOTANICAL GAZETTE [FEBRUARY 
known, is the only solid which transmits the entire Schumann 
spectrum. It is interesting from a biological point of view to note 
that the absorption bands of such substances as egg-white and 
gelatin begin in the longer wave lengths before we reach the 
Schumann region. 
In the writer’s observations, to be described below, unicellular 
organisms were exposed to the Schumann rays and observed 
microscopically during and after the exposure. The Schumann 
rays were produced by a discharge tube which was so made that 
it could be placed under the stage of a compound microscope in the 
position usually occupied by the condenser and other sub-stage 
attachments. When the discharge tube was in place, its fluorite 
window, through which the Schumann rays were emitted, was 
flush with the microscope stage. The Schumann light shone 
upward toward the microscope objective. The organisms were 
exposed above the discharge tube on a special microscope slide 
which contained a window of fluorite (glass is opaque to these 
rays). The regular sub-stage attachments could then be swung 
into place and the organisms observed under high magnifications. 
The effects produced by the light were immediate. There 
was a marked stimulation, followed by cytolysis, which, with a 
sufficient exposure, terminated in death. All of these changes 
were usually produced by an exposure of less than one minute’s 
duration. 
It was found that a given amount of exposure to the light pro- 
duced the same effect whether the exposure were continuous or 
interrupted. This made it convenient 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 temperature of the drop of water containing the organ- 
isms was measured by means of a thermal junction, the variable 
junction of which was placed beside the ————- under the 
coverglass. As the temperature did not rise 1° C. during the 
experiment, the changes produced could not have been due to 
heat. 
The length of time required for killing varied both with the 
species and with the individual organisms. In general, a small 
