2 4 o TUBERCULOSIS. 



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. 113). 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 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 al- 



t lowed to take place. 

 This deposit is ex- 

 amined in the same 

 way as the sputum. 

 It is, however, much 

 easier to obtain their 

 separation by means 

 of the centrifuge. If 

 this method is em- 

 ployed, bacilli can 

 usually be detected, 

 though sometimes 



FIG. 67. lubercle bacilli in urine ; show- , . , , 



ing one of the characteristic clumps, in which tneir number may be 

 they often occur. very small; here, 



Stained with carbol-fuchsin and methylene- pgDeciallv rCDCated 

 blue. x 1000. 



examinations may be 



necessary. The bacilli often occur in little clumps, as 

 shown in Fig. 67. In tubercular ulceration of the 

 intestine their presence in the faeces may be demonstrated, 



