416 BACTERIA PATHOGENIC TO MAN 



the rather late ones the serum fails. When the disease is far advanced 

 the serum is powerless. For immunizing 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. 



Duration of Life Outside of the Body. In cultures protected from the 

 air and light the plague bacilli may live one year or more. In the bod es 

 of dead rats they may live for two months. In sputum from pneu- 

 monic cases the bacilli lived ten days. Upon sugar sacks, food, etc., 

 they may live six to fifteen days. 



Resistance to Deleterious Influences. The bacilli resemble the colon 

 bacilli in their reaction to heat and disinfectants. Boiling for one to 

 two minutes kills them. Carbolic acid, 5 per cent, solution, kills cul- 

 ture in one minute, in 2^ per cent, in two minutes, etc. 



Bacteriological Diagnosis. When the lymph glands are acutely in- 

 flamed but not yet suppurated cut down on one and make cultures on 

 nutrient agar slanted in tubes. If pus has formed withdraw a little by 

 means of the hypodermic needle. There should also be made smears 

 from the suspected bubo, or in case of pneumonia from the sputum. If 

 the patient is dead, cultures from the spleen and heart's blood are also 

 taken when possible. Suspected animals, such as rats and mice, when 

 freshly killed, are examined as in man; when decomposed, rats and 

 guinea-pigs should be inoculated. 



Bacillus Icteroides. 



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 most yellow fever patients. 



Morphology. It resembles the colon bacilli in many characteristics. 

 The work of Reed and his associates having thoroughly overthrown the 

 claims of Sanarelli, its description is omitted with the exception of a few 

 notes. 



It stains readily with the ordinary aniline dyes, but not by Gram's 

 method. 



Biology. A motile, facultative, anaerobic, non-liquefying bacillus. 

 Does not form spores as far as known. Grows readily in all the ordinary 

 culture media at the room temperature, but best at 37 C. in the incu- 



