318 Manual of Veterinary llicrobiology. 



engorgements of the hypodermic inoculation of active 

 virus. He attributes to this substance the inflamma- 

 tions which sometimes occur, in the course of the 

 natural disease, in points remote from the thorax. 



Whatever opinion may be held regarding these in- 

 vestigationS;, the virulent agent of pleuro-pneumonia 

 exists in the serosity which flows in abundance when 

 a diseased lung is incised. Inoculation of this liquid 

 produces the following effects : 



In the subcutaneous cellular tissue a more or less in- 

 tense inflammatory engorgement results ; in regions in 

 which the connective tissue is loose and abundant 

 this reaction often assumes a severe, progressive and 

 occasionally gangrenous . character, and leads to 

 death ; the general effects of the virus are indicated 

 by a febrile reaction of greater or less intensity. 

 Pleuro-pneumonia is almost never observed as a con- 

 sequence of subcutaneous insertions. But the latter 

 confers immunity against later inoculations. 



The injection of the virus into the veins gives no 

 more characteristic pulmonary lesions ; it confers 

 immunity without any local manifestation, unless 

 some of the virus should fall on the perivascular 

 cellular tissue, in which case a dangerous tumor re- 

 sults. M. Thiernesse, however, observed pleuro-pneu- 

 monia after an injection of 35 grams in the jugular. 



Vacciiiaiion. — In 1852 "VYillems recommended pre- 

 ventive inoculation against this disease; his method 

 was put in practice in different places and the pre- 

 ventive action of Willemsian inoculation placed be- 

 yond doubt. 



The inoculation may be performed in three princi- 

 pal ways : by dermic, hypodermic, and intravenous 



