﻿2 The Philippine Journal of Science lai'i 



from cholera patients were used with no addition to make them 

 more palatable to the insects. 



The cockroaches devoured these fseces greedily; sometimes, 

 a single insect ingested 0.2 cubic centimeter. The insects were 

 transferred to new dry bottles after feeding and kept under 

 close observation in order to obtain faeces fresh for testing. 

 About six hours after their meal, the insects usually began dis- 

 charging liquid or semiliquid fasces, deeply tinted with carmine. 

 On the day following the feeding and on subsequent days, the 

 insects were given beef broth containing maltose, but no more 

 cholera vibrios or carmine. The maltose broth was fed to them 

 in order to obtain fresh fseces for testing. A discharge of faeces 

 usually followed this meal — often immediately. Carmine some- 

 times persisted in the faeces for six days after feeding. 



Tests were made by immediate microscopical observation, by 

 direct transfer to Dieudonne plates, and by transfer to peptone 

 for subsequent test on Dieudonne plates. All vibrios were tested 

 by a specific agglutinating serum. 



In 8 cockroaches fed with human faeces, cholera vibrios were 

 recovered from the insects' faeces six hours or more after feeding. 

 In one case they were found in comparatively small numbers 

 seventy-nine hours after feeding, and in several other cases they 

 occurred in greater or less numbers from twenty-four to forty- 

 eight hours after the ingestion of faeces. In one case they were 

 obtained twenty-four hours after feeding with a cholera culture. 



Actively motile cholera vibrios often appeared in enormous 

 numbers in the insects' faece«. In two cases, thirty-two hours 

 after feeding, they were so plentiful that the material was im- 

 mediately suitable for an agglutination test in hanging drop. 

 They were apparently as numerous as in the original human 

 faeces. In another insect, Dieudonne plates made directly from 

 faeces discharged two days after feeding showed thousands of 

 colonies. They were also seen in great numbers in faeces at less 

 intervals after the feeding. Generally, they seemed to diminish 

 in number after twenty-four hours. In two cases, faeces ob- 

 tained twenty-nine and one-half and thirty and three-fourth 

 hours, respectively, after feeding gave negative results, although 

 carmine still persisted in the faeces and these same insects had 

 passed faeces containing cholera vibrios five hours previously. 

 On the following day, the faeces of both these insects were free 

 from carmine and gave negative cholera tests. The cockroaches 

 were kept at a room temperature of from 29° to 31° C. 



The longevity of cholera vibrios in cockroach faeces after dis- 

 charge from the insect is probably short when the faeces are 



