246 THE UNIVERSITY SCIENCE BULLETIN. 
tract was packed with pale green matter like the culture! This proved 
to consist almost exclusively of the clear filaments of Mougeotia, the 
contents of the cells of which were in a state of disintegration. The 
free granular green matter was obviously derived from contents of the 
Mougeotia cells. No animal organisms or their remains found in these 
examinations. 
CULTURE 16126. (Rivularia.) 
History and Diagnosis. A porcelain-lined, granite-ware pan, which 
had been used for some time as a watering vessel for the birds and 
chickens, contained a layer of brownish material over the bottom and up 
the sides. Upon examination the material was found to consist of 
debris and Rivularia natans, no animals present. 
Corixids Added. Eggs of an undetermined Corixid were added and 
reared to second instar, when all died. The experiment was repeated 
with similar results. The water was not changed as frequently as might 
have been desired. Adults of R. acuminata and A. alternata failed to 
live more than a few days in this culture. 
CULTURE 1754. (Slime Diatoms.) 
History and Diagnosis. The rocks of upper Fall Creek were covered 
with long, brown strings of gelatin in March. This was found to con- 
sist of great quantities of the diatoms, Meridion, Fragilaria, etc., some 
filamentous Algz present but scattered. Placed some small stones, coated 
with this material, in a battery jar. 
Corixids Added. Placed Corixids here and they promptly began feed- 
ing. When examined surprisingly few diatoms were present, but quan- 
tities of filamentous alge, Mougeotia and Zygnema. 
For example, one female A. alternata had the fore part of the stomach 
packed with filaments of Zygnema as long as the entire mid intestine. 
This series shows selection in favor of the filamentous alge with dis- 
crimination against the gelatin embedded diatoms. 
CULTURE 17144. (Ankistrodesmus.) 
History and Diagnosis. Removed the gold fish from a jar in which 
they had lived for a long time. The jar and rocks were covered with 
dark-green growths. The water was very green. This was replaced 
by fresh water. The green growth was dominantly Ankistrodesmus 
falcatus. Some Scenedesmus and diatoms present as well as Cosmarium 
and Tetraspora. 
Coritxids Added. Twenty nymphs of P. buenoi added. Examined 
their stomach contents from time to time and they were always full of 
green chlorophyll material with Ankistrodesmus dominant and other 
Algez present with an occasional! rotifer. Green plants are taken first 
hand and in quantities. 
CULTURE 16169. (Botryococcus pure.) 
History and Diagnosis. Botryoccccus (a little alga in gelatin.) This 
culture was pure and growing in Knap’s solution. 
Corixids Added. The bug's always died within a day or so. 
