239 The Philippine Journal of Science 1915 
SUMMARY OF RESULTS 
Larve when fed on a medium containing cholera vibrios 
harbor these organisms in their intestinal tracts only as long 
as cholera vibrios are present in the medium and sufficiently 
plentiful in numbers not to be outgrown by other organisms. 
There is a transference of vibrios from the larve to the pupz 
and from the pupz to the imagines. This, however, is only 
possible when the larve and the pup are constantly changed 
to a sterile medium and drenched with 24-hour-old broth cul- 
tures of cholera vibrios. If this is not done, the vibrios are 
outgrown by the bacteria which are commensals in the intestines 
of the larvee and by the bacteria which are associated with putre- 
faction of the medium. 
In b and e¢ the failure of complete disinfection of the pupal 
surface was probably due to bacteria derived from the pupal 
intestine as it was shaken in Dunham’s peptone solution. 
The delay in the emergence of the flies is accounted for by the 
scarcity of nutriment present. 
SERIES IV 
Series 4 was undertaken to determine whether cholera 
vibrios are harbored in the intestinal tract of adult flies which 
have been fed upon media containing the vibrios, and the length 
of time they remain infective; and to determine if vibrios 
adhere to the surface of the body, and how long they remain 
infective. The following experiments were performed: 
a. On April 1 a Petri dish of Dieudonné’s medium, on which 
there was a good growth of cholera vibrios, was placed in a 
large stender dish containing human feces and covered with 
a layer of gauze. Three flies were seen to alight upon the gauze 
and enter the dish, after which it was securely covered and the 
flies allowed to remain therein for sixteen hours. The flies 
had a choice of both feeces and vibrios upon which to feed. At 
the expiration of sixteen hours the flies were removed and placed 
in separate flasks. 
b. When ten hours had elapsed since the feeding on vibrios, 
one fly was secured and placed in Dunham’s peptone and washed 
for five minutes. This tube, containing the bacteria washed 
from the fly’s surface, was incubated for twenty-four hours. As 
the growth was slight it was successively inoculated into three 
changes of Dunham’s peptone to enrich the vibrios which might 
be present. It was then inoculated on Dieudonné’s medium and 
examined. The plate contained pure cultures of cholera vibrios. 
