368 PA THOGENIC BA CTERIA.
sin i, and phenol 5. After staining they are washed in
distilled water containing i per cent, of acetic acid,
dehydrated in alcohol, cleared, and mounted. In such
preparations the bacilli may be found in little groups,
which are easily discovered, under a low power of
the microscope, as reddish specks, and readily resolved
into bacilli with the high power of the oil-immersion
In bacilli stained by this alkaline methylene-blue solu-
tion dark-colored dots may sometimes be observed near
the ends of the rods. These dots were at first regarded
as spores, but are now denominated polar granules, and
are thought to be of no importance.
The typhoid bacillus is both saprophytic and parasitic.
It finds abundant conditions in nature for its growth and
development, and, enjoying strong resisting powers, can
accommodate itself to environment much better than the
majority of pathogenic bacteria, and can be found in
water, air, soiled clothing, dust, sewage, milk, etc. con-
taminated directly or indirectly by the intestinal dis-
charges of diseased persons.
The bacillus is also occasionally present upon green
vegetables sprinkled with water containing it, and epi-
demics are reported in which the infection was traced to
oysters, from a certain place where the water was infected
through sewage. Newsholme1 found that in 56 cases
of typhoid fever about one-third was attributable to the
eating of raw shell-fish. In such cases the evidence
accumulated serves to show that the shell-fish were from
sewage-polluted beds. The bacillus probably enters milk
occasionally in water used to dilute it.
The resistant powers of the organisms have already
been described as great. They can grow well at the
room-temperature. The thermal death-point is given by
Sternberg as 60° C. The bacilli can, according to Klem-
perer and Levy, remain vital for three months in distilled
water, though in ordinary water the commoner and more
1 Brit. Med..Jour., Jan., 1895.