THE PHENOMENA OF INFECTION 459 



within from two to five days, but at the end of the second 

 or third week, at a time when the controls begin to develop 

 destructive changes, the inflammation begins to subside. 

 Later studies have confirmed and amplified these, and it 

 has been found that death may be induced within twenty- 

 four hours, by injecting a large amount of a living culture 

 into a tuberculous animal. 



The same difference between healthy and tuberculous 

 animals has been observed in their response to injections 

 of dead cultures of the tubercle bacillus. The first observa- 

 tion along this line, so far as we know, was made by Strauss 

 and Gamaleia, who found that when large numbers of dead 

 tubercle bacilli are injected into tuberculous animals death 

 results, while similar amounts are without immediate effect 

 upon healthy animals. 



When we come to tuberculin, every phase of its action 

 or its failure to act is explainable on the ground that the 

 tuberculous animal is a sensitized one. Koch found that 

 0.5 gram of his preparation killed tuberculous guinea-pigs, 

 and induced no symptoms in healthy ones. A fraction of 

 1 mg. may cause marked symptoms in a tuberculous man, 

 while many times this amount is borne easily by a healthy 

 man. The inflammatory reaction about local tuberculous 

 lesions caused by injections of tuberculin is explained by 

 the fact of the high degree of sensitization in their localities, 

 and the cleavage of the bacilli. The ophthalmic, cutaneous, 

 subcutaneous, and intravenous tests with tuberculin are 

 all typical sensitization reactions. Even in the failure to 

 respond to tuberculin seen in advanced tuberculosis we have 

 the condition known as anti-anaphylaxis, which simply 

 means that the anaphylactic ferment is partially exhausted 

 by the large amount of material supplied by the bacilli 

 in the body. 



There is a second factor in the failures of advanced cases 

 of tuberculosis to respond to the tuberculin test, which has 

 been generally overlooked, but to which we have already 

 referred 'in our discussion of so-called anti-anaphylaxis. 

 This is the fact that in such cases the body is saturated with 



