EXPERIMENTAL INOCULATION 



283 



number and in their site is met \vith in tuberculosis of other 

 animals. 



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. 108). 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 tubercular meningitis the bacilli can often be 

 found in the cerebro-spinal fluid obtained by lumbar puncture. 

 In cases of genito-urinary 

 tuberculosis they are 

 usually present in the 

 urine ; but as they are 

 much diluted it is diffi- 

 cult to find them unless 

 a deposit is obtained by 

 means of the centrifuge. 

 This deposit is examined f 

 in the same way as the ' 

 sputum. The bacilli often 

 occur in little clumps, as 

 shown in Fig. 83. In 

 tubercular ulceration of 

 the intestine their pres- 

 ence in the faeces may be 



rJATnnnatrafprl wa firt FIG. 83. Tubercle bacilli in urine ; showing 

 demonstrated, as was nrst Qne of the characteristic clum in whic g 



shown by Koch; but m they often occur. 



this case their discovery Stained with carbol-fuchsin and methylene- 



is usually of little im- blue - xloo - 



portance, as the intestinal 



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 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, 



