CHAPTER XX. 



Tuberculosis Microscopic appearance of miliary tubercles En- 

 capsulation of tuberculous foci Diffuse caseation Cavity-formation 

 Primary infection Modes of infection Location of the bacilli 

 in the tissues Staining peculiarities. 



SHOULD the animal succumb to neither of the septic 

 processes just described, then its death from tuberculosis 

 may be reasonably expected. 



When this process is in progress, alterations in the 

 lymphatic glands nearest the seat of inoculation may be 

 detected by the touch in from two to four weeks. They 

 will then be found to be enlarged. Though not constant, 

 tumefaction and subsequent ulceration at the point of 

 inoculation may sometimes be observed. Progressive 

 emaciation, loss of appetite, and difficulty in respiration 

 point to the existence of the tubercular process. Death 

 ensues in from four to eight weeks after inoculation. 

 At autopsy either general or local tuberculosis may be 

 found. The expressions of the tubercular process are 

 so manifold and in different animals differ so widely the 

 one from the other, that no rigid law as to what will be 

 found at autopsy can a priori be laid down. 



The guinea-pig, which is best suited for this experi- 

 ment, because of the greater regularity of its suscepti- 

 bility to the disease over that of other animals usually 

 found in the laboratory, presents, in the main, changes 

 which are characterized by a condition of coagulation, 

 necrosis, and caseation. This is particularly the case 

 when the infection is general, i. e., when the process is 



