248 THE UNIVERSITY SCIENCE BULLETIN. 
CULTURE 17165. (Chironomus.) 
History and Diagnosis. Early in the studies on the boatmen, it was 
found that hungry bugs would eat Chironomus larve. In this experiment 
some sand grains were placed in the bottom of a stender dish, and six 
Chironomus larve added. 
Corixids Added. Placed six P. buenoi here that had been in clear 
water two days. In two hours only three Chironomus larve remained. 
These were fortified beneath sand grains. These midge larve live in the 
sludge where Corixids forage. They live in tubes of their own spinning, 
and occasionally are eaten by the boatmen when the bug comes upon them 
in the course of its feeding. 
CULTURE 1650. (Balanced Aquarium.) 
History and Diagnosis. Into a circular glass aquarium jar, 9%x8 
inches, there had been placed about May 1 one of the Characee (Nitella) 
and some clear pond water. The culture came under observation the 
latter part of May, at which time the Nitella was still a thriving plant, 
and a small quantity of brownish sediment was upon the bottom of the 
jar (arranged in a ring perhaps two inches broad around it). The con- | 
tainer was kept nearly full of water by additions from the top. Corixid 
nymphs in their first instar had hatched from eggs brought in on the 
Nitella, and continued their development till they became adults. Bits 
of the carapace of a crayfish bearing eggs of Ramphocorixa acuminata 
were then added, and this species brought to adult stage. This culture 
then has considerable interest from the fact that two generations of 
Corixids were reared in it, one of A. alternata, a clear-pool type, and one 
of R. acuminata, a stagnant-pool type. 
The Nitella gradually disintegrated, adding its parts to the deposits © 
in the bottom of the jar, until by July 23 little was left of it. Surveys 
from time to time disclosed the following in the deposits: Much dis- 
organized plant matter, a few green spores of Alge, slender empty fila- — 
ments of Algze, some Pediastrum, various diatoms (abundant), and now 
and then the shell of an Ostracod. Ostracods and snails the only forms 
of animal life noted. The sediment, notably clear of animal life, adds 
another feature to the interest of this study. Corixids were observed 
repeatedly to feed upon the brownish deposit. Corixids were maintained © 
in this jar continuously for nearly four months. 
Corixids Added. Corixids of two species, A. alternata and R. acum- 
inata, were reared here. Some of the bugs were maintained here for 
four months. These bugs obtained their food from the deposits at the 
bottom. They did not prey upon the Ostracods feeding upon the sides 
of the jar. 
CONCLUSION. 
After carefully checking the results of feeding experiments 
it is safe to note the following: 
Corixids sweep in the organic ooze of the pool with its at- 
tendant populations, both plant and animal, the bulk of the 
