on contagious diseases of insects. He noted that certain 

 appendages to the alimentary canal in members of the 

 families Scutelleridae, Pentatomidae, and in some Lygaeidae 

 and Coreidae contained large numbers of "bacteria. In the 

 Coreidae and Lygaeidae the cecal structures are present in 

 one genus and ah sent in another. While th^ higher Hemiptera 

 (Pentatomidae, Scutelleridae, etc. ) invariably possess them, 

 they are always ah sent in the lower Hemiptera. According 

 to Forbes, the gastric pouches of grasshoppers, cockroaches, 

 and carahid "beetles do not commonly contain "bacteria. 

 Earlier (1857) Leydig had apparently observed microorgan- 

 isms in these ceca "but he was not aware of their true 

 nature. 



It was not until 191^ that Glasgow undertook a detailed 

 study of this relationship and brought out many interesting 

 facts concerning it. Among other things, he observed that 

 the bacteria from the different hosts vary a great deal in 

 their morphology though they are constant for each individ- 

 ual species of insect; that they range from minute coccus- 

 like bacilli to hugh spirochete-like forms; and that these 

 bacteria are apparently passed from generation to generation 

 through the egg since they appear early in the alimentary 

 tract of the developing embryo. This is one of the earliest 

 recorded instances of the hereditary transmission of bac- 

 teria in insects. To study the constancy of the presence 

 of bacteria in the ceca, Glasgow examined specimens of the 

 harlequin cabbage bug, Murgantia histrionica , secured from 

 widely separated points in the United States. In comparing 

 the flora of these specimens he found that the peculiar 

 large, spirochete-like forms were constantly present in the 

 ceca regardless of whether the specimen examined "was from 

 California or Maryland. " ' Few of the cecal bacteria could 

 be grown on ordinary culture media, although those from 

 Anas a tristis were cultured in nutrient broth. 



The mid-intestine of these ceca -possessing insects is 

 usually free of invading bacteria and protozoa commonly 

 present in many related insects. It appears that the 

 normal ceca- inhabiting bacteria inhibit the development 

 or exclude these foreign organisms altogether. Glasgow 

 believes that this is the chief function performed by the 

 cecal bacteria in the life processes of the host. He 

 assumes that the ceca merely provide a safe place for the 

 multiplication of normal bacteria. 



Kuskop (192*0 lists 23 insects of the family Penta- 

 tomidae, 7 of the family Coreidae, and k of the family 



