246 TUBERCULOSIS 



In discharges from tubercular lesions which are breaking 

 down, tubercle bacilli are usually to be found. In the sputum of 

 phthisical patients their presence can be demonstrated almost 

 invariably at some period, and sometimes their numbers are very 

 large (for method of staining see p. 101). Several examinations 

 may, however, require to be made ; this should always be done 

 before any conclusion as to the non-tubercular nature of a case is 



come to. In cases of genito- 

 urinary tuberculosis they 

 are usually present in the 



&& ^ urine; but as they are 



|^ much diluted it is difficult 

 to find them unless a de- 

 posit is obtained by means 

 of the centrifuge. This 

 deposit is examined in the 

 same way as the sputum. 

 The bacilli often occur in 

 little clumps, as shown in 

 Fig. 87. In tubercular 

 ulceration of the intestine 

 their presence in the faeces 

 may be demonstrated^ as 



FIG. 87. Tubercle bacilli in urine ; showing was first shown by Koch ' } 

 one of the characteristic clumps, in which ^ ut j n t ^ g cage fa^ <jis- 

 they often occur. . ni ,. -,. ,,-, 



Stained with carbol-fuchsin and methylene- p verv 1S ^ally of little 

 blue, x 1000. importance, as the intes- 



tinal lesions, as a rule, 



occur only in advanced stages when diagnosis is no longer a 

 matter of doubt. 



Experimental Inoculation. Tuberculosis can be artificially 

 produced in animals by infection in a great many different ways 

 by injection of the bacilli into the subcutaneous tissue, into 

 the peritoneum, into the anterior chamber of the eye, into the 

 veins ; by feeding the animals with the bacilli ; and, lastly, by 

 making them inhale the bacilli suspended in the air. 



The exact result, of course, varies in different animals and 

 according to the method of inoculation, but we may state 

 generally that when introduced into the tissues of a susceptible 

 animal, the bacilli produce locally the lesions above described, 

 terminating in caseation ; that there occurs a tubercular affection 

 of the neighbouring lymphatic glands, and that lastly there 

 may be a rapid extension of the bacilli to other organs by the 

 blood stream and the production of general tuberculosis. Of 



