566 BACTERIOLOGY. 



opment outside of the body like anthrax. In the form 

 of spores, however, reproduction may take place; and 

 by contamination with these, through deep wounds ac- 

 quired by animals in infected pastures, the disease is 

 spread. Possibly also it may originate through infec- 

 tion of the mouth and by feeding which would account 

 for the cases of symptomatic anthrax occurring in stall- 

 fed cattle (Hafner). 



It is well known to veterinarians that recovery from 

 one attack of symptomatic anthrax protects an animal 

 against a second infection. Artificial immunity to in- 

 fection can also be produced in various ways : by intra- 

 venous inoculations; or, in guinea-pigs, by inoculations 

 with bouillon cultures which have been kept for a few 

 days and as a result have lost their original virulence, 

 or with cultures kept in an incubating oven at a tem- 

 perature of 42 to 43 C.; or by inoculations made into 

 the extremity of the tail; or by inoculations with filtered 

 cultures, or with cultures sterilized by heat. 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 succumbed to the 

 disease, and which have been subjected to a suitable 

 temperature to ensure attenuation of the virulence of 

 the spores contained in it. Two vaccines are prepared, 

 as in anthrax a stronger vaccine by exposure of a por- 

 tion of the powder to a temperature of 85 to 90 C. 

 for six hours, and a weaker vaccine by exposure for the 

 same time to a temperature of 100 to 104 C. Inocu- 

 lations made with this attenuated virus (into the end of 

 the tail) the weakest first and later the stronger give 

 rise to a local reaction of moderate intensity, and the 

 animal is subsequently immune from the effects of the 



