36 AVENUES OF INFECTION 



tion of bacteria into the lymph and blood, but this cavity does not 

 receive the sanitary attention it should. Tartar is permitted to accu- 

 mulate about the teeth and cause atrophy of the gums. Particles of 

 food lodge between and about the teeth and furnish suitable material 

 for the growth of bacteria. Carious teeth are neglected and ports of 

 entry are directly opened up. Normal saliva has a distinct bacteri- 

 cidal action, but this is without practical effect on the pneumococcus, 

 the bacilli of diphtheria and tuberculosis, the spirochete of syphilis and 

 the organism of actinomycosis. The crypts of the tonsils offer places 

 for the lodgment and growth of bacteria, and from these localities 

 some of them find their way into the lymph and blood. Some hold 

 that tuberculosis frequently has its primary location in the tonsils 

 from which it passes through the lymph vessels to the apices of 

 the lungs. 



Many pathogenic bacteria pass through the nose and mouth with- 

 out causing local infection. It is not pleasant to state, but it is true 

 that much which is discharged from the bowels of one goes into the 

 mouth of another. This may be by short or long circuit, but the 

 result is likely to be unfortunate in either case. We drink water 

 infected with typhoid discharges and milk drawn with unclean hands, 

 and polluted with the excrement of man and beast. We enjoy fruits 

 and vegetables from orchards and gardens strewn with filth. We eat 

 bread and meat handled without gloves by baker and butcher, and 

 for all of this we pay heavy toll, as is shown by the morbidity and 

 mortality statistics. 



The Lungs. There has been much discussion whether tubercu- 

 losis is most frequently acquired by inhalation or by deglutition. Ani- 

 mals have been experimentally infected by both of these avenues by 

 numerous investigators from Villemin down to the present day, but 

 the opponents of the inhalation theory say that even when bacilli are 

 drawn with the air through the nose or mouth, they are deposited in 

 the pharynx and are swallowed. The reply to this is that colored bits 

 of dust when inhaled may be carried directly to the apices of the lungs 

 where they may be recognized. Furthermore, attention is called to 

 the inhalation of coal dust by miners and the resulting condition of 

 the lungs, known as anthracosis. The dog is quite readily infected 



