PATHOGENIC BACTERIA. 97 



They are found in the blood only when a vessel has come in 

 direct contact with a tubercular process through rupture or 

 otherwise. They have been found in other secretions, milk, 

 urine, etc. 



Man is infected as follows : 



Through wounds. Local tuberculosis. 



Through nutrition. Milk and meat of tuberculous animals. 



Phthisical patients swallowing their own sputum and causing 

 an intestinal tuberculosis. 



Inhalation. This is the most usual way, probably constitu- 

 ting the cause in T 9 - of the cases. 



The sputum of phthisical patients expectorated on the floors 

 of dwelling-houses in handkerchiefs, etc,, dries, and the bacilli 

 set free are placed in motion by the wind or rising with the dust 

 are thus inhaled by those present. When the sputum is kept 

 from drying by expectoration in vessels containing water, this 

 great danger can be avoided. 



Nearly all the cases of heredity can be explained in this man- 

 ner. The young children, possessing very little resistance, are 

 constantly exposed to the infection through inhalation and also 

 by nutrition. 



Immunity. No one can be said to be immune, though per- 

 sons who have been greatly weakened would offer less resistance 

 than health}^ individuals. 



Products of Tubercle Bacilli. The last }^ears have developed 

 some wonderful facts in relation to this important deadly bacillus. 

 In 1889, Dr. Dixon, then Professor of Hygiene at the Univer- 

 sity of Pennsylvania, spoke of a method of curing tuberculosis 

 in guinea-pigs and with products obtained from the bacillus ; 

 not much was thought of this statement at the time. 



In August, 1890, Koch, before the Medical Congress claimed 

 that he also had been able to cure tuberculosis in guinea-pigs, 

 and would be able to give some interesting facts later on. In 

 November he claimed that he had obtained reactions in man 

 similar to those in the guinea-pig, and believed that a cure was 

 at hand. 



In the excitement which followed this statement, the greatest 

 hopes were raised and the impossible expected. In January, 

 1891, Koch made public the manner of preparing the lymph or 



