GASTRIC CJECA OF THE HETEROPTERA. IOQ 



determine just how long after hatching the infection really occurs 

 under normal condition. A fairly complete series of the im- 

 mature stages of this insect was available at the time, and 

 starting with a half-grown nymph, the caeca of successively 

 younger individuals were examined until a stage only a few hours 

 old was reached without finding a single specimen free from the 

 infection. The next step was to examine a nymph immediately 

 after hatching and before there was any possibility of its having 

 fed; and as the caeca of this specimen also proved to be infected, 

 it became evident that the csecal organism itself must be trans- 

 mitted directly through the egg. 



In order to establish this point beyond question, embryos of 

 Murgantia in different stages of development were examined, 

 and it was found that in an embryo taken as early as forty-eight 

 hours before the time for hatching, the organism which had been 

 found uniformly in all the post-embryonic stages of the insect 

 also appeared in the embryo. The bacteria appear in that 

 section of the gut which is due to develop into the caecal apparatus 

 of the adult insect and which, owing to its pink color, can readily 

 be distinguished from the other embryonic divisions of the ali- 

 mentary canal. 



While the bacteria from the embryo of Murgantia, twenty-four 

 to forty-eight hours before hatching, are comparatively very few 

 in numbers, they nevertheless show the same characteristic, 

 spiral forms that are met with in the adult, although those from 

 the embryo are usually much shorter and decidedly more difficult 

 to stain. A considerable number of embryos of this insect were 

 examined in this way and, without exception, the caecal region in 

 all was infected with the same peculiar contorted organism. 



These observations on Murgantia naturally suggested that the 

 apparent contamination from the eggs of the squash bug might 

 also have been due to the caecal bacillus of this insect carrying 

 through the egg in a similar manner; although the fact that no 

 growth was secured from the eggs of Murgantia, in which the 

 caecal bacteria had been demonstrated microscopically, was rather 

 unfavorable to this view. This fact also seemed to indicate that 

 perhaps the caecal organism was so closely adjusted to conditions 

 in the body of the host insect that it would not develop readily on 

 artificial media. 



