396 
Thus far we have established the following: (a) Center Lake, during 
part of the year, has a region devoid of free oxygen. (b) A number of living 
organisms are found in it during this time. 
Many of these organisms are chlorophyl bearing. This made it desirable 
to determine, if possible, whether or not any light reached the bottom of 
this rather turbid lake. 
To answer this question a Brownie No. 0 camera, boiled in paraffine vw 
make it impervious to water, was fastened into a pail weighted in the bottom 
with lead to sink it. (See Fig. 2.) The lever of the shutter was arranged 
with strings running through opposite sides of the top of the pail (see Fig. 3), 
so that when the camera was sunk to the desired depth the shutter could he 
opened, exposing a bit of film arranged between two microscopic slides 
which were taped around the edges, serving the double purpose of keeping 
the film dry and acting as a check. (See Fig. 4.) 
After an exposure of five minutes, the shutter was closed by means of the 
other cord and the camera raised to the surface. The film was developed. 
The exposed part of the film was distinctly darkened, showing that there 
is some light at the bottom of the lake. The intensity and quality of this 
light remains to be determined. 
BIBLIOGRAPHY. 
’ 
Birge, E. A., and Juday, C.: 
(11) The Inland Lakes of Indiana. Wisconsin Survey Bulletin No, 22. 
Conn, H. W., and Webster, L. W.: 
(08) A Preliminary Report on the Algae of the Fresh Waters of Con- 
necticut. Conn. State Geology & Nat. History Surv., pp. 1-78. 
(05) The Protozoa of the Fresh Waters of Connecticut. 
Edmondson, C. H.: 
(06) The Protozoa of Iowa. Proceedings of the Davenport Academy 
of Science. Vol. XI, pp. 1-24. 
Wolle, F.: 
(94) The Diatomaceae of N. A. Comenius Press, Bethlelem, Pa. 
Sedgwick, A.: 
