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 I/* 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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