1 86 MARSHALL HERTIG. 



the bacteroids occurring within the tissues or body cavity of 

 the roaches is not precluded, since all the writer's specimens of 

 Periplaneta americana were heavily infected with a gregarine, 

 Diplocystis sp., inhabiting the body cavity. Glaser did not 

 mention any control experiments showing that the washing of 

 the roach with alcohol or other leagents was successful in steril- 

 izing the surface of the roach. It is conceivable that such 

 reagent might fail to sterilize the areas where one segment 

 overlaps another. In referring to the definite wanderings of 

 the bacteroids in the body of the roaches and in the yolk of the 

 egg, Glaser stated that the organisms in the species studied by 

 him were motile. It is not clear whether motility of the bacte- 

 roids was observed directly, or whether the motility of the spirilla 

 in cultures was referred to. In the writer's work many fresh 

 preparations of the bacteroids obtained from five species of 

 Blattidse, including Periplaneta americana, were studied. No 

 suggestion of motility was observed in any case. In view of 

 the conflicting evidence and the technical difficulties involved, 

 Glaser's evidence that the spirilla represent the bacteroids in 

 culture would seem to be inadequate. 



As concerns Blatella germanica and Blatta orientalis, the work 

 of Javelly and the writer indicate quite definitely that the 

 bacteroids do not grow on routine culture media, and that 

 Bacillus cuenoti of Mercier is a contaminator. The entirely 

 negative results of the writer in the culture of the bacteroids of 

 Periplaneta americana, combined with the evidence from the 

 other species, would seem to furnish strong presumptive evidence 

 that the spirillum obtained by Glaser does not represent the 

 cultural form of the bacteroids of this species. 



BIBLIOGRAPHY. 

 Blochmann, F. 



'87 Ueber das regelmassige Vorkommen von bakterienahnlichen Gebilden in 



den Geweben und Eiern verschiedener Insekten. Zeitschr. f. Biologie, 



24: 1-15. 

 Krassilschtschik, M. 



'89 Sur les bacteries biophytes. Note sur la symbiose des Pucerons avec les 



bacteries. Ann. Inst. Pasteur, Vol. 3. 

 '90 Ueber eine neue Kategorie von Bacterien (Biophyten) die im Innern eines 



Organismus leben und ihm Nutzen bringen. 8. Kongress russ. Naturf. 



Arzte. Sitz., 16 Jan. i?go. (Bericht in Biol. Centralbl., Vol. 10.) 



