250 



THE INFECTIOUS DISEASES. 



the air spaces of the lungs, are capable, as they slowly disintegrate, of 

 stimulating the cells of the tissues where they lodge to proliferation, 

 and to the production of new tissue morphologically similar to tubercle 

 tissue in its various phases ' (Fig. 124). Necrosis of the new-formed 





FIG. 124. INFLAMMATORY NODULE (PSEUDO-TUBERCLE) IN THE LIVER OF THE RABBIT INDUCED BY 

 THE INTRAVENOUS INJECTION OF DEAD TUBERCLE BACILLI. 



Most of the dead bacilli have disintegrated, setting free the bacterial proteid which has stimulated the new 

 cell growth. A few fragments of the bacilli, however, still remain. 



cells may occur, but this differs in some respects from the coagulation 

 necrosis induced under the usual conditions. Dead tubercle bacilli are 

 also markedly chemotactic and capable of causing local suppuration and 



It would seem probable then that while the power of the tubercle 

 bacillus to induce necrosis and the fever which in many cases indicates a 

 systemic intoxication may be due to metabolic products of the living 

 germ, the local lesions characteristic of exudative and productive inflam- 

 mation may be due to a peculiar bacterial proteid which is set free by the 

 disintegration of the bacilli in the tissues. 



Complex Factors in the Tuberculous Process. 



It is well in studying the characters of tuberculous inflammation to remember that 

 in its progressive phases there are two factors at work : first, those which lead to cell 

 proliferation and new tissue formation, which is apparently a reparative and conserva- 

 tive process ; second, those which are inhibitory or damaging or destructive ; and, finally, 

 that both sets of factors are commonly active together. It may still be considered doubt- 



Ziegler's Beitr., Bd. xxxiii., p 



