242 TUBERCULOSIS. 



Post mortem, in addition to the local and glandular chafiges, 

 an acute tuberculosis is usually present, the spleen being 

 specially affected. This organ is swollen, and is studded 

 throughout by numerous tubercle nodules, which may be 

 minute and grey, or larger and of a yellowish tint. If death 

 has been long delayed, calcification may have occurred in 

 some of the nodules. Tubercle nodules, though rather 

 less numerous, are also present in the liver and in the lungs, 

 the nodules in the latter organs being usually of smaller 

 size though occasionally in large numbers. The extent 

 of the general infection varies ; sometimes the chronic 

 glandular changes constitute the outstanding feature. 



Intraperitoneal injection of pure cultures produces a 

 local lesion in the form of an extensive tubercular infiltra- 

 tion and thickening of the omentum, sometimes attended 

 with acute tubercles all over the peritoneum. There is 

 a caseous enlargement of the retroperitoneal and other 

 lymphatic glands, and later there may be a general tuber- 

 culosis. Intravenous injection produces a typical acute 

 tuberculosis, the nodules being usually more numerous and 

 of smaller size, while death follows more rapidly the larger 

 the numbers of bacilli injected. Guinea-pigs, when fed 

 with tubercle bacilli, or with sputum or portions of tissue 

 containing them, readily contract an intestinal form of 

 tuberculosis, lesions being present in the lymphoid tissue 

 of the intestines, in the mesenteric glands, and later in the 

 internal organs. 



Whatever be the path of infection when a guinea-pig 

 has died after inoculation, attempts to cultivate the bacilli 

 may fail, though they are present in an apparently normal 

 condition in the lesions. The bacilli have, in such a case, 

 probably died in the struggle of the tissues against them, 

 but the intracellular toxines which still remain have been 

 absorbed and have caused the death of the animal. 



Rabbits are less susceptible than guinea-pigs, and in them 

 the effects of subcutaneous inoculation are very variable ; 

 sometimes the lesions remain local, sometimes a general 

 tuberculosis is set up. Otherwise the reactions are much of 



