BACTERIA IN DISEASE. 163 



microbes produce a lesion at the point where they are in- 

 troduced, as in the familiar cases of boils and carbuncles 

 when pyogenic bacteria enter the skin, or of the tubercles 

 found in the lungs when the bacilli lodge in the respiratory 

 tract. However, there are cases of septicemia and pyemia 

 in which the most careful search fails to reveal the place at 

 which the bacteria entered. The bacilli of plague usually 

 produce no reaction at the point of entrance. 



It is probable that tubercle bacilli may pass through thin 

 epithelial surfaces and lodge in the deeper structures un- 

 derneath, where they produce definite lesions. For exam- 

 ple, they may pass by the lungs and enter the bronchial 

 glands, and form tubercles in that situation. 



Experiments on animals have shown that bacteria may 

 be very rapidly disseminated after their introduction. The 

 inoculation of mice, for instance, with anthrax bacilli has 

 been known to prove fatal, although the wound was washed 

 immediately with the strongest antiseptic solutions or the 

 part amputated within a few minutes. 



The manner in which infectious agents reach human 

 beings varies considerably. Generally speaking, the most 

 important element will be found to be direct or indirect 

 connection with another case of the same disease. W. H. 

 Park was able to cultivate diphtheria bacilli from bed cloth- 

 ing soiled by the expectoration of diphtheria cases. Bald- 

 win has shown that tubercle bacilli may be found on the 

 hands of patients having pulmonary tuberculosis, especially 

 those who expectorate on handkerchiefs. 



Excepting under certain special conditions, the Air will 

 not contain the germs of disease. The dried pulverized 

 sputum of cases of pulmonary tuberculosis may float in the 

 atmosphere as dust which will contain tubercle bacilli. 

 Fliigge states that powerful expiratory efforts like coughing 

 and sneezing may carry tubercle bacilli with small particles 



