BIOLOGY OF BACTERIA. 61 



hours. Cultures made within five minutes showed con- 

 fluent colonies of the bacilli, which became fewer and 

 fewer in number, until after two hours not a trace of a 

 bacillus prodigiosus could be found. 



Wurtz and L,ermoyez assert that the nasal mucus exerts 

 a germicidal action, but this is not substantiated. These 

 writers conclude that the bacteria were carried away by 

 the action of the cilia and trickling mucus. 



It seems to have been proven by Buchner that micro- 

 organismal infection may take place through the lungs 

 without definite breach of continuity of the alveolar 

 walls. He mixed anthrax spores and lycopodium powder 

 together, and caused mice and guinea-pigs to inhale them. 

 Out of the 66 animals used in his experiments, 50 died of 

 anthrax and 9 of pneumonia. Our knowledge of the dis- 

 position of foreign particles in the lung probably explains 

 such infection by assuming that the presence of the lyco- 

 podium attracted numerous leucocytes to the affected air- 

 cells; that these took up the powder, and with it the 

 spores; and that the leucocytes, being cells of very sus- 

 ceptible animals, were unable to resist the growth into 

 bacilli of the spores which they had carried into the 

 lymph-channels. 



On the other hand, it has been shown that when 

 the entering spores are unaccompanied by a mechanical 

 irritant like the lycopodium powder, but are inspired 

 in a pulverized liquid, infection takes place much less 

 readily. 



Tuberculosis and pneumonia are in all probability 

 generally the result of the inspiration of the specific 

 organisms. 



(c) The Skin and the Superficial Mucous Membranes. 

 The entrance of bacteria into the tissues by way of the 

 skin is probably extremely rare if the skin is sound. 

 Numerous experimenters have caused infection by rub- 

 bing bacteria or their spores upon the skin. It would 

 seem probable that in these cases there must have 

 been some microscopic lesions into which the bacteria 



