DISEASES TRANSMITTED BY THE COCKROACH 387 



Bacillus subtilis Ehrcnborg, an organism frequently found in air, 

 water, and soil, seldom pathogenic, was fed in three series of experiments, 

 b^' Cao, in conjunction with otlicr foods to starved roaches of Blaffa 

 orienfalis. In two cases he obtained slight patliogenicity inducing local 

 suppurations but no killing of the experimental host. 



Bacillus ^^tifo simile'' Cao, a bacillus described by Cao resembling B. 

 tijplwsus, was isolated by Cao in three out of four series of experiments 

 from the feces of B. orientalis in strains of varying virulence, which could 

 in some cases be increased by feeding to the cockroaches in connection 

 with other foods. 



Bacillus tuberculosis Koch, the cause of TUBERCULOSIS, was fed 

 by Kiister to Blatta orientalis and later recovered from its feces. 



Bacillus typhosus Eberth, the cause of TYPHOID FEA'ER, is con- 

 sidered by Herms and Nelson, and also by Longfellow, as capable of being 

 transmitted by the cockroach. 



ThaUophyta: Fungi: Spirillaceae 



Spirillum cholerae Koch, the cause of ASIATIC CHOLERA, can be 

 carried by cockroaches as demonstrated by Barber in the Philippines, He 

 fed Periplaneta americana on human feces infected with the cholera 

 vibrios and these roaches passed living vibrios in their feces up to 79 

 hours, and when fed on cholera cultures, up to 24< hours. Active, motile, 

 cholera vibrios often appeared in enormous numbers in the insects' feces, 

 A cockroach was also observed to disgorge portions of its meals at inter- 

 vals of ten, twenty, and sixty minutes after feeding, sufficient time for it 

 to travel from the closet to the human food. The sixty minute sample 

 contained many cholera vibrios. No vibrios were found in the salivar}^ 

 discharge of the insect. 



Spirillum metcliniK'ovi (Gamaleia). This organism, cause of a FOWL 

 DIARRHEA, was experimented with by Cao, who determined that Blatta 

 orientalis which had not fed for 45 days and of Avhich the feces only con- 

 tained a mild strain of Bacillus coli, when fed on a feeble strain of this 

 organism, passed it through its feces deprived of its pathogenicity. He 

 fed cultures of the organism at the same time witli sterile bread and also 

 with fresh flesh with the same result ; but Avlicn cultures of this feeble 

 strain were fed in connection with a diet of bread and an infusion of 

 putrid beef liver, a diet of bread and a 1 per cent infusion of putrid 

 peptone, and a diet of bread and an infusion of putrid beef liver, they 

 regained intense pathogenicity. 



