174 MANUAL OF BACTERIOLOGY. 



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. 



Tubercle bacilli may pass through thin epithelial surfaces 

 and lodge in the deeper structures underneath, where they 

 produce definite lesions and leave no trace to mark the point of 

 entrance. For example, they may pass by the lungs and enter 

 the bronchial glands, and form tubercles in that situation. 



Ravenel has shown that they pass through the walls of the 

 intestines without causing any lesion there, and produce tuber- 

 culosis in the lungs and elsewhere. 



Experiments on animals have shown that bacteria may be 

 very rapidly disseminated after their introduction. The inocu- 

 lation 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 agencies concerned in the transfer of infection have been 

 referred to in Part II., Chapter III. In all cases, however, 

 there is direct or indirect connection with another case of the 

 same disease. W. H. Park was able to cultivate diphtheria 

 bacilli from bedclothing soiled by the expectoration of diph- 

 theria cases. Baldwin has shown that tubercle bacilli may be 

 found on the hands of patients having pulmonary tuberculosis, 

 especially those who expectorate on handkerchiefs. Winslow 

 found bacillus coli communis on the hands of 5 per cent, to 19 

 per cent, of those examined; his observations suggest the 

 possibility that typhoid bacilli can be carried in a similar 

 manner. 



Direct Contact. — Many diseases are conveyed from a sick 

 individual to a healthy person by direct contact as in gonor- 



