408 Veterinary Medici?ie. 



phthisis. But not only phthisis may reasonably be considered 

 to have one of its modes of origin in the breathing of an atmos- 

 phere contaminated by respiration, but other lung diseases, bron- 

 chitis and pneumonia, appear also to be more common under 

 such circumstances.' 



Villemin in 1865, published his investigations in which he had 

 produced tuberculosis in a great number of animals, by inserting 

 particles of fresh tubercle or injecting the tuberculous sputa of 

 man into the subcutaneous connective tissues, the peritoneum 

 and the trachea. There resulted in nearly every case a chronic 

 disease, the marked phenomena of which were caseated centers 

 devolving from firm inflammatory nodules in the seat of inocula- 

 tion, in the adjacent lymphatic glands, in the lungs, serous mem- 

 brane, liver, spleen and kidneys. The centers of such nodules 

 were at first transparent and grayish, but soon the center under- 

 went necrobiosis, forming a soft cheesy mass the size of a pin's 

 head, and gradually enlarging to that of a pea, a bean, a hazel 

 nut or larger. After a period of about 14 days the lymphatic 

 gland nearest the seat of injection could be ftlt as a firm pea- 

 like nodule, and in two weeks more a second gland on the line of 

 the lymph circulation, had become enlarged and nodular, while 

 the first, now the size of a large beau, had probably undergone 

 distinct softening. This became adherent to the skin, burst and 

 discharged continuously or at intervals with little or no tendency 

 to heal. If killed at this date, the animal showed only the open 

 sore and a chain of nodular pea-like caseated lymphatic glands 

 leading up from it. The lungs might be apparently sound, but 

 the spleen and liver usually showed miliary elevations on the sur- 

 face, with clear grayish centers, as viewed under a magnifying 

 glass, opaque patches were found on the omentum, and the lym- 

 phatic glands of the mesentery, of the portal fissures of the liver 

 and of the Hilus of the spleen were distinctly enlarged and re- 

 sistant. If not killed, the subject usually died 100 to 120 days 

 after inoculation, and then the lungs were found studded with 

 tubercules miliary or larger and more or less caseated ; the bron- 

 chial mediastinal, subdorsal, pectoral, prepectoral, phrenic, mesen- 

 teric, hepatic, and splenic lymphatic glands were more or less 

 enlarged and caseated, while the liver and spleen were enlarged 

 and studded with multiple tubercles. Guinea pigs give the most 



