184 PROTEIN POISONS 



destroyed by lysis within an hour. There is some lytic 

 destruction of tubercle bacilli in the peritoneum of a 

 healthy guinea-pig, but this does not compare in rapidity 

 and completeness with that occurring in the tuberculous 

 animal. But why is the action of this lytic agent manifested 

 so effectively against the bacilli of the second inoculation 

 while those of the first apparently proceed in uninterrupted 

 growth? One of Hamburger's experiments 1 may throw 

 some light on this question. He made his reinoculation 

 subcutaneously on each side. On the left he injected a 

 small dose, on the right a large one. On the left there was 

 no development; on the right a tuberculous nodule developed. 

 We infer from this and similar observations made by others 

 that the lytic agent which destroys the tubercle bacillus 

 and which is produced in larger amount in tuberculous 

 than in normal animals, because the cells of the former have 

 been sensitized, is stored in the cells as a zymogen, and 

 is activated only when tuberculoprotein is brought into 

 contact with the cell, and possibly is active only, or is 

 most active, in statu nascendi. The ferment is capable of 

 destroying only a given amount of bacilli or is wholly 

 inactive in the presence of a great excess of substrate, 

 or its action is soon interrupted by the accumulation of 

 fermentative products. However, it is quite certain that 

 all the bacilli of the second inoculation are not always 

 killed because it may happen according to observations 

 of Hamburger that some months after the second inoc- 

 ulation, during which time there may have been no 

 evidence of infection, tubercular processes appear and 

 develop like a primary infection. Whatever the true 

 explanation, it is a fact that the tuberculous animal is more 

 resistant to additional infection than the normal animal is 

 to primary infection. This led Lowenstein 2 to say: "Only 

 the tuberculous organism is tuberculosis-immune." Ham- 



1 Beitrage z. klin. d. Tuberculose, xii. 



2 Handbuch d. path. Mikroorganismen, Kolle u. Wassermann, zweite 

 Auflage. 



