318 The Philippine Journal of Science 1915 
bacilli are weak in competing with the intestinal bacterial flora 
of larvz and that they are soon outgrown by the more vigorous 
organisms mentioned by Cao. 
A. W. Bacot,(40) in 1911, employed B. pyocyaneus in order 
to determine its persistence from the pupz to the imagines of 
Musca domestica. His technique and results are as follows: 
A vessel containing sterile sand, mixed with baked milk, cooked 
rice, gristle of meat, and other food, had added to it the eggs 
of M. domestica. Several cultures of B. pyocyaneus were added 
to this, and the growing larvz were fed thereon. 
Some of the larve were secured; their surfaces were disin- 
fected by washing them in 5 per cent lysol for five minutes. 
These surface-sterilized larvee when crushed and inoculated into 
broth showed a growth of B. pyocyaneus. 
Flies just as they emerged were secured, and their surfaces, 
likewise, were sterilized in lysol. These flies had no opportunity 
to infect themselves by feeding upon B. pyocyaneus. When 
crushed and inoculated into broth, they showed a growth of 
B. pyocyaneus. 
Ledingham confirmed these results by securing the pupz of 
flies, and in place of sterilizing the surface with lysol, held them 
between the fingers, searing the anal extremity with a red-hot 
knife-point, passing a blunt pipette into the intestines and with- 
drawing the contents which were then mixed with salt solution 
and sprayed on plates. This modified technique was more satis- 
factory, because pupal disinfection by lysol is difficult, owing to 
the fact that, when the pupz are shaken in broth or sterile 
salt solution, bacteria escape from their interiors. 
Ledingham, (41) in 1911, having confirmed Bacot’s work, per- 
formed a series of experiments to ascertain whether or not an 
organism like B. typhosus could adapt .itself to conditions pre- 
vailing in the larval and pupal interior in competition with 
organisms of a more hardy nature. His work includes the 
following: 
In the first series eggs of M. domestica were placed in a 
sterile dish, containing sterile sand mixed with sterilized food in 
the form of mashed potatoes, meat, and turnips. This mash was 
repeatedly drenched with broth cultures of typhoid bacilli. 
While the larve were growing and feeding, the mash devel- 
oped a strong ammoniacal odor. 
As this mash was so liberally drenched with cultures of ty- 
phoid bacilli, plates of McConkey’s medium were inoculated with 
the mash to ascertain whether or not B. typhosus would be the 
