f 



PATHOGENIC BACTERIA. 293 



bacilli may travel through the lymph-spaces and affect adja- 

 cent tissues, some of them reaching the nearest group of 

 lymph-nodes. In tuberculosis of the lungs it is usual also to 

 find tubercles in the bronchial lymph-nodes, and in tuber- 

 culosis of the intestines there is also tuberculosis of the 

 mesenteric lymph-nodes. The disease may travel along the 

 serous surfaces and become widely scattered throughout a 

 cavity like that of the pleura or peritoneum. The bacilli 

 may be expelled on some mucous surface and be carried 

 along it to infect some point farther on, as happens when 

 the larynx becomes infected in tuberculosis of the lungs, 

 and when in the same disease tuberculous sputum is swal- 

 lowed and leads to infection of the intestines. Finally, the 

 infectious material may enter the blood-vessels, especially 

 the veins, and be swept along with the blood-current to 

 become scattered generally throughout the body. In such 

 cases we are likely to have general or acute miliary tubercu- 

 losis. Almost every organ of the human body may be in- 

 fected by tuberculosis. Among the most common may be 

 mentioned the lungs, the lymph-nodes, the bones, the intes- 

 tines, the skin, the meninges, and the serous membranes. 



Infection, as far as we know, is always to be attributed 

 directly or indirectly to some preexisting case of tubercu- 

 losis in man or the lower animals. The entrance into the 

 body is most commonly by way of the lungs, where also 

 tuberculous disease is commonest in man, going by the 

 name of consumption. This is doubtless due to the prev- 

 alent habit of expectorating in public places. Out of fifty- 

 six samples of sputum collected in street cars by Dr. W. G. 

 Bissell, City Bacteriologist in Buffalo, four were tubercu- 

 lous. In forty-eight samples taken from the floors of a 

 public building by Dr. C. R. Orr, of the pathological labor- 

 atory of the University of Buffalo, tubercle bacilli were 

 found three times. According to the researches of Nuttall, 



