496 PATHOGENIC ANAEROBIC BACILLI. 



according to the method of Toussaint and Chauveau ; a temperature 

 of 4:2 to 43 C. is suitable. The pathogenic virulence of spores may 

 also be attenuated by subjecting them to dry heat a temperature of 

 80 to 100 C. maintained for several hours. For the production of 

 immunity in cattle Arloing, Cornevin, and Thomas recommend the 

 use of a dried powder of the muscles of animals which have suc- 

 cumbed to the disease, and which has been subjected to a suitable 

 temperature to insure attenuation of the pathogenic virulence of the 

 spores contained in it. Kitt, who has made extended experiments 

 with this bacillus, recommends that the muscles be first dried at 32 

 to 35 C. and then powdered. Two vaccines are then prepared a 

 stronger vaccine by exposure of a portion of the powder to a tem- 

 perature of 85 to 90 C. for six hours, and a weaker vaccine by ex- 

 posure for six hours to a temperature of 100 to 104 C. (dry heat). 

 Inoculations made with this attenuated virus the weakest first and 

 subsequently the least attenuated give rise to a local reaction of 

 moderate intensity, and the animal is subsequently immune from the 

 effects of the most virulent material. Immunity may also be secured 

 by intravenous inoculations ; or, in guinea-pigs, by inoculations with 

 bouillon cultures which have been kept for a few days and as a re- 

 sult have lost their original virulence, or with cultures kept in an in- 

 cubating oven at a temperature of 42 to 43 C. ; or by inoculation 

 with a very minute quantity of a pure culture ; or by an inoculation 

 made into the extremity of the tail ; or by inoculations with filtered 

 cultures (Roux and Chamberlain), or with cultures sterilized by heat 

 (Kitasato). It has been claimed (Roux) that animals which have 

 been made immune against symptomatic anthrax are also immune 

 against malignant oedema. But in a carefully conducted series of 

 experiments Kitasato was unable to confirm this ; he found that 

 guinea-pigs which had an immunity against the most virulent cul- 

 tures of the Rauschbrand bacillus succumbed invariably to malig- 

 nant oedema when inoculated subcutaneously with the bacillus of 

 malignant oedema. 



