METHODS AND CHANNELS OF INFECTION. 529 



washes the microorganisms out of the wound. Contused wounds are 

 especially dangerous inasmuch as there is not a free flow of blood and 

 also there is a good chance for the growth of anaerobic bacteria such as 

 those of tetanus, malignant oedema, symptomatic anthrax and emphy- 

 sematous gangrene. 



The mucous membranes of the nose, throat and mouth are quite 

 resistant to infection. The epithelial coat, the mechanical action of 

 the mucus and saliva, and possibly the slight bactericidal action of the 

 saliva are the barriers. Infections of the thin non-resistant membrane 

 of the new-born do occur and necrosis sometimes results (noma). The 

 mucous membrane of the mouth and throat is frequently the seat of pri- 

 mary infection when it is injured. The actinomycotic fungus usually 

 enters a lesion in the mucous membrane made by straws. The 

 ducts of the salivary glands also serve as points of entrance for certain 

 infectious agents. The tonsils are very commonly the seat of infections 

 especially with the Strept. pyo genes and Strept. pneumonia. Septicaemias, 

 for example those occurring in diphtheria, and especially in scarlet 

 fever, arise from infection of the tonsils with Strept. pyogenes. These 

 structures are also the primary point of invasion in cases of acute rheu- 

 matism. The nasal mucous membrane is more permeable to infectious 

 agents than that of the oral cavity. The microorganisms of acute 

 epidemic meningitis, measles, leprosy and glanders most frequently enter 

 the body through lesions in the membranes of the nose. Infection may 

 be carried into the nose directly or pass from the conjunctiva through 

 the naso-lachrymal duct. 



The flora found in the eye is quite extensive. The conjunctiva is 

 not infrequently the seat of primary infections. The pyogenic cocci and 

 the M. gonorrhcece are among the common infecting agents. It is possible 

 that certain points of infection are provided by the conjunctiva being 

 injured by dust particles. The tears are not markedly bactericidal 

 and only serve to wash the eye mechanically. Infections of the con- 

 junctiva are frequently very severe. There is no doubt also that other 

 pathogens are caught in the eye and washed into the nose where they 

 set up infections or are carried through the membranes to set up infec- 

 tions elsewhere. M . intracellularis var. meningitidis, of epidemic menin- 

 gitis, is known to pass in this way and possibly Bact. pestis, of the 

 plague. 



Infectious microorganisms after being taken into the body through 

 34 



