20 



md named Bacillus cellulosam f ermentans . Schutte (1921) 

 found that cellulose is digested "by the larva of Hydromyza 

 livens , "but apparently without the aid of "bacteria. 



It should "be remembered, when one is considering the 

 role of cellulose- fermenting "bacteria in the nutrition of 

 insects, that in most phytophagous insects the food passes 

 through the gut so rapidly that no great amount of fermen- 

 tation is likely to take place. The "breakdown of cellulose 

 "by "bacteria is usually too slow a process to "be initiated 

 and completed in the few hours during which food remains 

 in the gut. On the other hand, cellulose-splitting "bacteria 

 are often associated with the food ingested "by insects and 

 for this reason cannot "be completely ignored. Furthermore, 

 certain insects, such as the Lamellicorn larva, possess 

 "fermentation chambers" which are probably used for such 

 purposes. 



In 1919 Roubaud asserted that adult tsetse flies were 

 exclusively hemophagous. The "blood ingested "by the flies 

 was digested only in the middle section of the intestine 

 where the epithelial cells include symbiotic organisms. 

 According to Roubaud, these organisms play an important 

 part in the digestion of the "blood. Wigglesworth (1929) 

 states, however, that there is no evidence that these 

 organisms play any part in the digestion of the "blood. 



Fermentation chambers . As has already "been mentioned, 

 the gut of certain insects, notably Lamellicorn larvae, 

 possess special sacs or chambers containing "bacteria 

 which are probably responsible for "breaking down the 

 cellulose ingested by the insect. Cuticular areas "bearing 

 "branched spines occur on the walls of the chamber. The 

 thin cuticle "between these areas is pierced "by fine canals. 

 It appears that most of the digestion and absorption takes 

 place within this chamber since the tiny particles of 

 cellulose and wood are retained here for ldng periods of 

 time and are acted upon "by the cellulose -fermenting 

 "bacteria therein. 



According to Werner (1926), larvae of Potosia (Cetonia), 

 which feed on the decaying pine needles found in ant heaps, 

 thrive only at those temperatures optimum for the cellulose - 

 fermenting "bacteria. Similar fermentation chambers are 

 also possessed by certain Lipulids. There are some in- 

 sects, such as the larvae of Dorcus and Osmoderma , which 

 possess "fermentation chambers" filled with "bacteria which 

 apparently do not "break down the cellulose they ingest. 



