360 MANUAL OF BACTERIOLOGY. 



intestines to the lungs without leaving any trace of their passage. 

 The others hold that where animals are fed with tuberculous 

 material, particles are insufflated in their passage down the 

 esophagus. The fact that cases have been found in which the 

 tonsils were the only seat of tuberculosis in the whole body 

 shows that in such cases at least the infection was from the 

 air passing over the tonsils. 



The dissemination of the tubercle bacillus is doubtless 

 very largely due to the prevalent 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 tuberculous. In forty-eight samples taken 

 from the floors of the public building by Dr. C. R. Orr, of the 

 pathological laboratory of the University of Buffalo, tubercle 

 bacilli were found three times. According to the researches 

 of Nuttall, a person suffering from tuberculosis may expec- 

 torate many millions of tubercle bacilli in the course of twenty- 

 four hours. Coughing and sneezing may serve to dissemi- 

 nate the bacilli (see page 175). 



Concerning the occurrence of tubercle bacilli in cow's milk 

 and butter, and in beef, see pages 151, 351 and 152. 



Cases have been recorded in which the disease was trans- 

 mitted from the mother to the child in the uterus; how fre- 

 quently this happens is uncertain. It is usual to attribute 

 greater importance to an inherited tendency to tuberculosis 

 than to the inheritance of the tubercle bacilli themselves.* 



Agglutination of the tubercle bacillus is said to occur with 

 the serum of cases of tuberculosis under certain circumstances. 

 The reaction does not seem likely to be of practical value. 



Tuberculin is made by concentrating a culture of tubercle 

 bacilli grown in glycerin-bouillon to one-tenth of its original 

 volume, over a water-bath, and filtering through a sterilized 



*On tuberculosis of the placenta see Warthin. Journ. Infect. Dis. Vol. IV. 

 1907. pp. 347-368. 



