300 THE TUBERCLE BACILLUS 



month there is severe tuberculosis of the peritoneum, omentum and mesentery : 

 the spleen is enlarged : tubercles are visible in the spleen, liver and lungs and 

 sometimes in the kidneys : the pleural cavities sometimes contain an excess 

 of fluid and the pleurae are covered with small grey tubercles. " With 

 smaller and smaller doses of tubercle bacilli the lesions in the organs begin 

 to resemble more and more those produced by sub-cutaneous inoculation" 

 (English Commission).] 



4. Intra-pulmonary inoculation. There is a caseous focus at the point of 

 entry of the inoculation needle and the lungs are spotted with grey tubercles 

 in the adjacent area. In the abdominal viscera the lesions are similar to those 

 following sub-cutaneous inoculation. 



5. Inhalation. Guinea-pigs are readily infected with tuberculosis by causing 

 them to inhale dried and finely powdered tuberculous sputum or dust mixed 

 with tubercle bacilli from cultures. The animal dies with well-marked 

 caseous broncho-pneumonia. 



6. Ingestion. Guinea-pigs have been infected by feeding them with the 

 milk of a cow suffering from tuberculous phthisis (Villemin and Parrot, Klebs). 

 In animals infected in this way it occasionally happens that there are no 

 lesions in the intestines. [When feeding guinea-pigs with tubercle bacilli 

 Cobbett sometimes observed a generalized infection involving the lungs but 

 pulmonary tuberculosis apart from a generalized infection did not occur.] 



B. Rabbits. 



Rabbits are not so susceptible to tuberculosis as guinea-pigs. A fatal 

 result does not always follow the inoculation of a small amount of tubercu- 

 lous material. Occasionally the local lesion is of long standing before the 

 disease becomes generalized. Inoculation of bovine or avian tubercle bacilli 

 is followed by a more severe infection than inoculation with human tubercle 

 bacilli. 



1. Sub-cutaneous inoculation. According to the amount of virus inocu- 

 lated the animal will live for from one to several months. A local induration 

 (tuberculous chancre) is formed but the glands are often not affected while 

 the lungs are, as a rule, the first to show tubercles. 



The human tubercle bacillus often fails to kill rabbits when inoculated sub-cutane- 

 ously. On an average, four out of five strains of human tubercle bacilli produce 

 only a local lesion and this undergoes spontaneous resolution. The disease resulting 

 from inoculation of bovine bacilli is always more severe. 



2. Intra-peritoneal inoculation. The course of the disease is more rapid. 

 Tubercles are found on the peritoneum, spleen, liver etc. Death often occurs 

 before the disease has reached the thorax. 



3. Intra-pulmonary inoculation. Inhalation. The disease runs the same 

 course and presents the same lesions as in the guinea-pig. Frankel and 

 Troje have produced caseous pneumonia in rabbits as a result of intra-tracheal 

 inoculation. 



4. Inoculation into the anterior chamber of the eye. By inoculating the 

 bacillus into the anterior chamber of the eye the progress of the lesions can 

 be easily followed. During the third week, the iris becomes covered with 

 tuberculous granulations, the eye swells, the aqueous humour becomes cloudy 

 and occasionally the whole eye is transformed into a purulent abscess : the 

 glands of the neck hypertrophy and infection becomes disseminated giving 

 rise to a generalized tuberculosis of the Villemin type (p. 298). 



5. Intra-venous inoculation. The disease produced by intra-venous 

 inoculation may be of one of two types : 



(a) Miliary tuberculosis. According to the amount of material inoculated 



