244 THE UNIVERSITY SCIENCE BULLETIN. 



was killed and the stomach seen to be packed with green 

 chlorophyll. The contents of this stomach were fixed in 8 per 

 cent formaldehyde plus copper acetate, and mounted in glyc- 

 erine jelly, together with mounts of the Spirogyra before and 

 after being foraged over by the bug. Drawings of these prep- 

 arations are shown on plate XXX. The next day the ex- 

 periment was repeated with two first instar nymphs of the 

 same species. They, too, proceeded to feed at once as the adult 

 had done. 



Culture 16217. (Ground Elodea.) 



History and Diagnosis. Ground-up tips of Elodea and changed water 

 repeatedly to wash out the free green chlorophyll matter. Studies of the 

 grindings show Elodea, bits of tissue and single cells. Scenedesmus, 

 threads of Gonatozygon and Oscellatoria, diatoms, large and small, a 

 few heterotrichs, etc. 



Corixids added. Every examination made of the stomach contents of 

 the bugs after foraging here showed the tract packed with green ma- 

 terial. This consisted of cells of Elodea, filaments of Oscellatoria and 

 Gonatozygon, desmids and the like. One A. alternata contained a thread 

 of Gonatozygon 1 mm. long. Splendid demonstrations, all of them, of the 

 plant feeding tendencies of these bugs. 



Culture 17129. A. (Ground Cattail.) 



History and Diagnosis. Gathered some dead cattail leaves from the 

 marsh by the Field Station. Soaked them in water for a few days and 

 then ground them up by means of a meat grinder. The result was a 

 flocculent brown mass of fine matter. This material was ground up on 

 May 9 and the water changed frequently until the 11th, when Corixids, 

 adult and nymphs, were added. They began foraging promptly. Ten 

 days later they were still doing nicely. Examination of the forage 

 showed much finely divided tissue, some Algae, mostly unicellular, such 

 as Tetraspora and Englenae. The rotifers, dead and alive, make up the 

 bulk of the animals. There are plenty of the cellulose tissue of the cat- 

 tail, bits no larger than the Algse. 



Corixids Added. The examination of the stomachs of the bugs always 

 showed them filled with brownish material, superficially like the forage. 

 A close examination, however, indicated the aVsence of Typha tissue, and 

 the abundance of the ramate jaw parts of rotifers. Much brown matter 

 that could not be analyzed, and mixed with it the green cells of the 

 Tetraspora, Englenas and some filamentous Algae. Even the large Arcto- 

 corixa interrupta avoided taking in the Typha tissue, although it ate bits 

 of Algae of larger dimension. The ground Typha serves as a stock for 

 the growth of organisms eaten by the boatmen. 



Culture 17129 B. (Ground Cattail, sterile.) 



History and Diagnosis. Same as in 17129A. Boiled this repeatedly to 

 sterilize it. Did not use the sterilizer, however, so the ground Typha 

 soon spoiled even if boiled. 



