1901] MICROSCOPICAL JOURNAL 41 
large animals (horses, sheep, goats). The serum of these 
immunized animals contains an antitoxin capable not only 
of preventing the disease, but also of curing it in mice and 
guinea-pigs and probably inman. MHaffkine in his exper- 
iments followed the line of preventive inoculation as em- 
ployed against cholera. Bouillon cultures were used, in 
which floating drops of butter were employed to make the 
islands of plague bacilli float. The cultures were grown 
for a month or so, successive crops of the island-stalac- 
tite growth as it formed, having been precipitated by agi- 
tating the tube. In this manner there was obtained an 
‘intense extra-cellular toxin” containing large numbers 
of the bacilli. The culture was killed by exposure to a 
temperature of 70 °C. for one hour, and the mixture used 
in doses of about 3 c.cm. as a preventive inoculation. 
A most interesting collection of statistics, showing in a 
convincing manner the importance of the Haffkine pro- 
phylactic, is that of Leumann of Hubli. The figures, to- 
gether with a great deal of interesting information upon 
the subject, can be found in the paper upon “A Visit to 
the Plague Districts in India” by Barker and Flint. The 
immunity conferred by the Haffkine prophylactic in doses 
of 1c.cm. is of considerably longer duration, lasting about 
a month. The preparation must not be used if the per- 
sons have already been exposed to infection, and is possi- 
bly in the incubation stages of the disease, as it contains 
the toxins of the disease and greatly intensifies the exist- 
ing condition. When injected into healthly persons it al- 
ways produces fever, local swelling and malaise. Wysso- 
kowitz and Zabolotny, whose studies have already been 
quoted, used 96 monkeys in the study of the value of the 
‘‘plague-serums,” and found that when the treatment has 
begun within two days from the time of inoculation, the 
animals can be saved, even though symptoms of the dis- 
ease aremarked. After the second day, the treatment can- 
not be relied upon. The dose necessary was 20 c. cm, of 
