Microbic Diseases Individually Considered. 201 



virus, as well as the ingestion of forage soiled by very 

 active virulent matters, can also occasion the disease. 

 In the case of cutaneous wounds, the characteristic 

 tumor develops at the place of inoculation itself; in 

 the two latter contingencies the bacilli multiply in the 

 blood and determine tumors in places where they meet 

 with an opening by which they may penetrate into 

 the connective or muscular tissue. Rupture of some 

 of the fibers of the muscles, alteration of the vascular 

 endothelium (perhaps by the products of the bacilli), 

 the production of even a slight wound which may be 

 overlooked, are all so many factors on which depend 

 the seat of the primary and secondary tumors. 



Attenuations. Preventive inoculations. — The virus be- 

 comes spontaneously attenuated when it is left in con- 

 tact with the air; diminution of its virulence can be 

 obtained artificially by means of antiseptics and heat. 

 The latter agent supplied to MM. Arloing, Cornevin, 

 and Thomas, the means of preparing virus of various 

 degrees of intensity. The natural serosity of the 

 specific lesions can be attenuated to difi'erent degrees 

 by a temperature of from 65° to 70°, maintained for a 

 greater or less length of time. These authors, how- 

 ever, operated by preference with serosity dried at the 

 temperature of 30° to 35°; the dried virus is, in reality, 

 more fixed than the fluid serosity, because the spores 

 are much more resistant when dry than when in a 

 moist condition. This dried virulent substance with- 

 stands temperatures of 80° to 90° without losing any 

 of its activity; reduced to powder and moistened, 

 then brought to temperatures varying between 60° and 

 110°, it becomes progressively attenuated. The virus, 

 attenuated to such an extent that it is no more fatal, 



