HUNGERFORD: AQUATIC HEMIPTERA. 241 
in demonstration for a long time. For detailed studies of di- 
gestion the usual histological methods must be followed. 
SPECIAL STUDIES. 
Carmine Feeding. - 
As stated under the heading of general habits, the use of 
the flat pale of the fore legs in feeding is easily observed. It 
occurred to the writer that if powdered carmine were sprinkled 
over the sediment on the bottom of the aquarium it might be 
taken up by the boatmen in their feeding and serve as an index 
to the time it takes for food to pass through the digestive 
tract. If found in the stomach in large quantities it would add 
further evidence to the belief that they scoop the food into the 
mouth in quantities. Several experiments and demonstrations 
have been made by placing the powdered carmine upon the 
sediment in the bottom of the jars and then turning in Corixids 
to feed. If hungry the boatmen will begin at once, and a dis- 
section of one of them after ten or fifteen minutes feeding will 
prove that they take up the carmine and organic ooze in 
quantities. The digestive tracts have been found packed from 
end to end with the red material. On plate XXX is given 
a figure in color of the digestive tract of a Corixid after 
feeding upon carmine covered forage. Permanent mounts of 
digestive systems in balsam make useful slides for demonstrat- 
ing this point, since the walls of the stomach become clear and 
the red material within gives striking preparations. 
This carmine-feeding experiment was attacked from every 
angle in order to avoid drawing any false conclusions. A care- 
ful reading of the notes obtained will indicate how easily one 
could fall into errors by superficial examinations. The experi- 
“ment was planned and executed by the following outline: 
TyYPHA CULTURE 17129. 
A. Survey of culture. 
) B. Stender with culture and carmine. 
a. Survey culture after 24 hours. 
F b. Place Corixids here that have been in clear water for 24 hours. 
q 1. Forage 1 minute and examine. 
2. Forage 5 minutes and examine. 
3. Forage 20 minutes and examine. 
4. Forage 20 minutes, remove to clear water for 30 minutes and 
examine. 
5. Forage 20 minutes, remove to clear water for 130 minutes and 
examine. 
16—Sci. Bul.—1669 
