Il6 HUGH GLASGOW. 



which was usually used in the proportion of 1-500. The mercuric 

 chloride solution is best applied with a bit of absorbent cotton 

 held in a pair of old forceps. In this way the entire body of the 

 insect can be thoroughly scrubbed w T ith the disinfectant, so that 

 any folds, such as those between the body segments, will certainly 

 be moistened. After the bichloride solution has completely 

 dried, which may be very well hastened by passing the insect back 

 and forth before a Bunsen flame, the flat edges of the abdomen 

 are clipped off, from near the posterior end up to the thorax, with 

 a pair of fine scissors which have been previously flamed. The 

 top of the abdomen immediately back of the thorax may be cut 

 across with sterile scissors and the resulting flap formed of the 

 entire dorsal wall of the abdomen may then be lifted back with a 

 pair of flamed forceps, leaving the abdominal viscera exposed. 



Usually in forms such as the larger Coreidse and Pentatomida?, 

 the alimentary canal is considerably coiled in the posterior half 

 of the abdominal cavity, and is covered above by a thin layer of 

 fatty tissue which must be moved to one side before the cseca 

 can be reached. 



The caeca may be readily distinguished from the other divisions 

 of the alimentary canal, as they are pure glistening white in the 

 Coreidae or tinted yellow or pink in many of the Pentatomidae. 



In making cultures from the caeca, the usual procedure was to 

 open the abdomen with sterile instruments, in the manner just 

 described, and after removing the dorsal fat body, to clip out a 

 small section from near the middle of the caecal system, which was 

 then quickly removed with flamed forceps to a tube either of 

 sterile salt solution or bouillon, the final cultures being made 

 from this tube. 



For reasons which have already been explained, the first 

 serious attempt at cultivating the caecal bacteria was made with 

 Murgantia histrionica; and unfortunately the work was confined 

 for a long time to this species and a few other pentatomids, in 

 an attempt to discover some means by which their peculiarly 

 characteristic bacteria could be made to develop on artificial 

 media. 



When the work was first undertaken with Murgantia, it was 

 planned to remove a section of the caeca to a tube of sterile salt 



