ATTEMPTS TO CULTIVATE BACTEROIDS OF BLATTID/E. 185 



bacteriocytes were transferred directly to media and incubated. 

 In the writer's experiments with Periplaneta americana, three 

 tubes of bouillon were inoculated with bacteroids from three 

 oothece, employing the technique described above. These three 

 cultures remained sterile. A portion of the fat-body of a nymph 

 was obtained by pulling apart the segments of the abdomen as 

 described above, and a tube of bouillon inoculated. No growth 

 occurred. In making a second transfer from this same nymph, 

 the digestive tract was injured and contamination resulted. 

 No other cultures were made from this species. While the 

 number of cultures made from Periplaneta americana was limited, 

 the results are seen to be in perfect agreement with those obtained 

 by both Javelly and the writer for Blatella and Blatta. If the 

 spirillum obtained by Glaser from Periplaneta americana, and 

 which grows so readily in a great variety of routine media, 

 actually represents the cultural form of the bacteroids of this 

 species, it is difficult to account for the consistently sterile 

 cultures obtained by the writer. 



It was not stated by Glaser whether his technique yielded 

 pure cultures of the spirilla in all cases, or whether contaminations 

 were encountered. The subject of contamination was not 

 discussed, either as concerns organisms in the cultures other 

 than the spirilla or as to the possibility of the spirilla themselves 

 being organisms other than the bacteroids. In view of the 

 conflicting results of various investigators and the small size 

 and filthy habits of the cockroach, the matter of possible con- 

 tamination would seem to be a paramount consideration. In 

 Mercier's work the flaming of the ootheca did not prevent 

 contamination, and indeed, from his control experiments in 

 which he obtained sterile cultures from the clear liquid bathing 

 the eggs, it would appear that Bacillus cuenoti was obtained from 

 within the egg. Javelly obtained contamination in cultures 

 from the fat-body. In the writer's work, contamination was 

 encountered in cultures from both ootheca? and fat-body. It 

 would seem impossible entirely to avoid contamination, except 

 when employing single bacteroids isolated by the Barber or 

 equivalent technique. The possibility of organisms other than 



