DEC 30 18M 



BULLETIN 



OF THE 



Illinois State Laboratory 



OF 



Natural History. 



VOLUME IV. 



Ahticle I. — Bacteria Normal to Digestive Organs of He- 

 miptera. By S. A. Forbes. 



In 1833 Leon Dufour described and figured in his "it!e- 

 cherches sur les Hemipi^res,''* under the non-committal 

 name of "cordons valvuleux," some curious appendages 

 of the alimentary canal in Scutelleridse, Pentatomidae, 

 and certain Coreidse, misinterpreting their structure, how- 

 ever, and expressing no opinion as to their function, 

 which, in fact, he called a mystery .f These organs had 

 been previously distinguished by Ramdohr (1811), and 

 they have since been several times referred to by ento- 

 mologists as glands or follicles secreting a digestive fluid, 

 presumably pancreatic. My own entomological studies 

 did not make me particularly acquainted with structures 

 of this class until 1888, in the autumn of which year, 

 while studying the contagious diseases of the chinch bug 

 {Blissus leucopterus) I made some dissections of that 

 insect, isolating the alimentary canal and searching dif- 

 ferent parts of it for the source of a bacterial infection 

 discovered in the fluids of chinch bugs when crushed under 

 the microscope. This bacterial development I thus traced 

 to certain coecal appendages of the small intestines so 

 unlike the '^cordons valvuleux'^ of Dufour's descriptions, 

 that it did not for a time occur to me to connect the 

 two; but in the course of some general dissections of 



* Pp. 14'J-]51, etc . and figs. 1. 2, C. 13, 19. 21. 

 + i'p. 150. 171. 



