DISTRIBUTION OF BACILLI. 433 



optimum temperature being that of the body. The influenza 

 bacillus is a strictly aerobic organism. 



The powers of resistance of this organism are of a low 

 order. PfeirTer found that dried cultures kept at the 

 ordinary temperature were usually dead in twenty hours, 

 and that if sputum were kept in a dry condition for two 

 days, all the influenza bacilli were dead, or rather 

 cultures could be no longer obtained. Their duration of 

 life in ordinary water is also short, the bacilli usually being 

 dead within two days. From these experiments PfeirTer 

 concludes that outside the body in ordinary conditions 

 they cannot multiply, and can remain alive only for a short 

 time. The mode of infection in the disease he accordingly 

 considers to be chiefly by direct contact by means of 

 mucus, etc. 



Distribution in the Body. The bacilli are found chiefly 

 in the respiratory passages in influenza. They may be 

 present in large numbers in the nasal secretion, generally 

 mixed with a considerable number of other organisms, but 

 it is in the small masses of greenish-yellow sputum from 

 the bronchi that they occur in largest numbers, and in 

 many cases almost in a state of purity. They occur in 

 clumps which may contain as many as 100 bacilli, and 

 in the early stages of the disease are chiefly lying free. As 

 the disease advances, they may be found in considerable 

 numbers within the leucocytes, and towards the end of the 

 disease a large proportion have this position. It is a 

 matter of considerable importance, however, that they may 

 persist for weeks after symptoms of the disease have dis- 

 appeared, and may still be detected in the sputum. 

 Especially is this the case when there is any chronic pul- 

 monary disease. They also occur in large numbers in the 

 capillary bronchitis and catarrhal pneumonia of influenza, as 

 PfeirTer showed by means of sections of the affected parts. 

 In these sections he found the bacilli lying amongst the 

 leucocytes which filled the minute bronchi, and also 

 penetrating between the epithelial cells and into the super- 

 ficial parts of the mucous membrane. Their presence seta 

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