332 



TUBERCULOSIS 



of evidence is in favor of the former view that the stimulus to pro- 

 liferation and the latter itself precede the coagulation necrosis. In any 

 event, if necrosis occurs first, it is very insignificant, and the pro- 

 liferation with the appearance of karyokinetic figures is very obvious 

 and impressive in the first stage of the formation of the tubercle. In 

 this first stage the tubercle bacilli are found partly between the cells 

 and partly inside of the protoplasm of epithelioid cells. Whenever 

 bacilli have gained entrance into the cell protoplasm, they evidently 

 cause a profound disturbance of the cell metabolism. The bacilli- 

 infected cell grows and becomes larger by the absorption of nutritive 

 material and its nucleus divides, but not the cell protoplasm itself. 



Fio. 148 



Section through tubercular tissue of pleura of a horse. (Author's preparation.) 



This process continues, and very large cells with many nuclei are 

 formed. The latter are frequently distributed around the periphery. 

 The bacilli infecting such a large multinudear giant cell are generally 

 found in the protoplasm at some distance from the nuclei. The 

 protoplasm of the giant cell early shows evidences of necrobiosis or 

 coagulation necrosis or granular degeneration. While such giant 

 cells are forming the epithelioid cells increase in number. Among 

 them, and particularly around them at some distance from the point 

 where the bacilli are most numerous, small round cells with round, 

 granular, deeply staining nuclei and small protoplasmic bodies appear. 

 These cells are proliferated young connective-tissue cells, which have, 



