Bacteria Normal to Digestive Organs of Herniptera. 3 



Balbiani's observations, however, (reported in Comptes 

 Bendus, Vol. 103, p. 952) to the effect that bacterial 

 forms introduced in the blood of insects are taken up by 

 the cells of the pericardial tissue and destroyed therein, 

 give a certain probability to the hypothesis that these 

 seeming bacteria of cockroaches are really such. It is 

 true that Balbiani's statements are limited to the peri- 

 cardial tissue in the vicinity of the heart; but as Kowa- 

 levsky has shown* that this tissue is intermingled in 

 many insects with the so-called fatty bodies, it is not 

 unlikely that a more general and critical search would 

 have shown the cells in question to have the same func- 

 tions wherever found. 



There can, however, be no doubt as to the nature of 

 the objects found in the ccecal appendages of the Hemip- 

 tera above mentioned. They not only present every 

 visible characteristic of micrococci and bacilli, but by 

 their reaction to stains, their resistance to prolonged 

 treatment with solutions of caustic potash, and espe- 

 cially and conclusively by the success of our culture ex- 

 periments with both fluid and solid media, they answer 

 to all the tests applicable to the recognition of bacteria. 



These coecal structures are probably shown in their 

 simplest form in Pyrrhocoridee (see Dufour, p. 171, and 

 figures 17 and 21), although in the absence of speci- 

 mens of this family for microscopic examination I can 

 only repeat Dufour's surmise that the small and variable 

 c(ecal pouches of the small intestine in these Hemiptera 

 are homologues of the complicated apparatus of Anasa 

 and Euschistus. The next simplest form of this organ 

 which I have thus far seen, is that of the chinch bug) 

 where it consists of five to eight large coeca radiating 

 from a common point of attachment on the intestine 

 about .2 mm. behind the third stomach. These coeca are 

 about .12 mm. in diameter, and average 1.5 mm. in 

 length. They are straight or slightly contorted, with 

 smoothly rounded ends, and are nearly filled, when in 

 normal condition, with large, pale, loosely-attached, sub- 



• Biologisches Centralblatt, Vol. IX., p. U. 



