BACILLUS ICTEROIDES. 609 
prevented. In some of the early cases and in many of 
the rather late ones the serum fails. When the disease 
is far advanced the serum is powerless. For immu- 
nizing purposes the serum should be valuable, and a 
single injection would probably give protection for 
several weeks. 
Haffkine, in India, has recently applied his method 
of preventive inoculation to the bubonic plague, as he 
previously did with cholera and apparently with equally 
good results. This method consists in an inoculation 
of dead cultures, and is essentially a protective rather 
than a curative treatment. It gives after six to ten - 
days a considerable immunity, lasting a month or more. 
By means of these two methods of inoculation, along 
with strict quarantine regulations, it is to be hoped 
that this disease which under the name of Black 
Death once decimated the populations of the earth, and 
which in the East still causes great mortality at times, 
may finally be greatly restricted or even stamped out 
altogether. 
BACILLUS ICTEROIDES (Bacillus of Yellow Fever). 
In 1897 Sanarelli announced the discovery of a micro- 
organism which he claimed to be the specific cause of 
yellow fever. This he called the ‘ bacillus icteroides.’’ 
It is found in the circulating blood and in the tissues of 
yellow fever patients. 
Morphology. Short rods with rounded extremities, 
single or united in pairs in cultures and in groups in 
the tissues, from 1y to 2 in length, and generally two 
to three times longer than broad. Somewhat polymor- 
phous. It resembles the colon bacilli. 
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