THE BACILLUS FOR SMALL ANIMALS 157 



show evidence of tubal desquamation, which appears 

 to be most marked in the tubuli contorti. In the 

 animals that receive a single injection, this inflamma- 

 tory condition does not increase much in severity, and 

 in a very short time the organ regains, more or less, 

 its healthy state. When multiple doses are given, the 

 changes described above are intensified, the kidneys 

 show marked haemorrhagic tubal nephritis, and in 

 cases that have survived for any length of time an 

 early interstitial nephritis may also be present. The 

 nodular formations which follow the intravenous 

 injection of most of the other acid-fast bacilli have not 

 been observed with Johne's bacillus, and we have been 

 unable to trace the passage of the bacilli through the 

 kidney by means of stained sections. However, the 

 bacilli are undoubtedly excreted by this organ, since 

 they can occasionally be demonstrated in smears made 

 from the stringy albuminous material usually present 

 in the pelvis of the kidney. All attempts to obtain 

 cultures from the urine have failed, although numerous 

 specimens were taken from twenty-four hours to two 

 months after the inoculation of the animal. 



Congestion of the lungs is evident after twenty-four 

 hours, and masses of acid-fast bacilli are found sur- 

 rounded by a few epithelioid cells. The cells rapidly 

 increase in number, and small foci appear in the inter- 

 stices of the alveoli ; these foci resemble on casual 

 observation the early stage of a miliary tubercle. The 

 majority of the baciUi are quickly phagocytosed, but 

 those in clumps remain extracellular, and are sur- 

 rounded en masse by epithelioid cells, lymphocytes, etc. 

 The intracellular bacilli are often found in characteristic 

 wreath-like formations, but they disappear completely 

 on the tenth to the fifteenth day after the last inocula- 

 tion. In animals receiving a single injection, the lung 



