BACILLI IN TUBERCULAR DISCHARGES. 221 



both in their number and in their site is met with in tuber- 

 culosis of other animals. Cellular necrosis and caseation 

 occur in proportion to the numbers of the bacilli present, 

 much more readily in some animals than in others, prob- 

 ably owing to different degrees of susceptibility of their tissues. 

 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 demon- 

 strated almost invariably at some period, and sometimes 

 their numbers are very large (for method of staining see 

 p. 102). In cases of genito-iirinary tuberculosis they are 

 often present in the urine ; but as they are much diluted 

 it is difficult to find them unless a very complete forma- 

 tion of deposit is allowed to take place. This deposit is 

 examined in the same way as the sputum. It is, how- 

 ever, much easier to obtain their separation by means of 

 the centrifuge ; and 

 if this method 

 is employed, they 

 can usually be found, 

 though sometimes 

 their number may 

 be very small. The 

 bacilli often occur in 

 little clumps, as shown 

 in Fig. 6 1. In tuber- 

 cular ulceration of the 

 intestine their presence 

 in the faeces may be 

 demonstrated, as was 



first shown by Koch ; 

 , . ,. , . FIG. 6 1. Tubercle bacilli in urine ; show- 

 but in this case their ing one of the characteristic clumps, in which 

 discovery is Usually Of they often occur, 

 little importance as Stained with carbol-fuchsin and methylene 



the intestinal lesions, blue " x I000 ' 



as a rule, occur only in advanced stages when diagnosis 



is no longer a matter of doubt. 



Experimental Inoculation. Tuberculosis can be arti- 



