462 Philippine Journal of Science 1919 
which time they can no longer be found. If bile is adminis- 
tered, however, these same animals continue to excrete the 
vibrios for indefinite periods, the exact length of time not having 
been determined definitely. 
In 1916, in Bilibid Prison,(4) 600 carriers (8.2 per cent of 
the population) were found; a total of 112,577 stool examina- 
tions were made. A word as to the technic: A sterile swab was 
plunged into each man’s feeces and thus inoculated; this swab 
was placed in a test tube containing about 2 cubic centimeters 
of plain agar of a reaction of —1.0 to phenolphthalein. The 
purpose of the agar is simply to prevent the drying out of the 
inoculum. Upon receipt at the laboratory, 10 cubic centimeters 
of a 2 per cent peptone solution were added, and the tubes in- 
cubated over night. In the morning hanging drops from these 
peptone tubes were examined for suspicious motility, and the 
tubes showing it were set aside for further culturing. Dieu- 
donné plates were used and, after streaking, were incubated for 
a further twenty-four hours. All suspicious colonies were fished 
out, emulsified in a sterile salt solution, and tested for agglutina- 
tion. For the latter test an immune serum having a titer of 1 
to 4,000 was used in a dilution of 1 to 500. The cholera vibrio 
agglutinates promptly with this, and nothing but the true cholera 
vibrio will give a positive reaction. There are vibrios, however, 
that correspond with the true organism in every way except 
agglutination; these may or may not be true cholera vibrios. 
The majority of these vibrios are hemolytic; that is, in blood- 
agar plates a clear zone of hemolyzed blood is produced about 
the colony. Some authors have reported strains of cholera vib- 
rios producing hemolysis also. In the light of our present knowl- 
edge, however, it may be safely accepted that any vibrio that 
does not agglutinate promptly on being brought into contact with 
a drop of a 1 to 500 dilution of a known cholera-immune serum 
of high titer is not a true cholera vibrio. 
That these nonagglutinating vibrios bear some more or less 
intimate relation to cholera seems to be borne out by the fol- 
lowing, from O’Connell: (1) 
These choleroid organisms are an extremely interesting phenomenon. 
Their relationship to true cholera may be said to have been established 
but not defined. Bacteriologists in service in the Far East have noted 
their appearance in specimens subjected to microscopical examination 
immediately before and during cholera epidemics. They are not known 
where cholera is not or has not been recently. Their morphology and 
biological characteristics are such that it is impossible to distinguish 
them from true cholera organisms by microscopic examination. 
