INFECTIOUS DISEASES OF CATTLE. 445 



fraught with danger, unless those who handle them are thoroughly 

 aware of the danger of scattering the virus by careless handling in 

 wagons which are not tight. As a rule, the persons in charge of such 

 transfer have no training for this important work, so that deep burial 

 is to be preferred. Burning large carcasses is not always feasible. 

 It is, however, the most certain means of destroying infectious mate- 

 rial of any kind, and should be resorted to whenever practicable and 

 economical. All carcasses, whether buried, rendered, or burned, 

 should be disposed of without being opened. When stables have 

 become infected they should be thoroughly cleaned out, and the solu- 

 tion of chloride of lime freely applied on floors and woodwork. The 

 feed should be carefully protected from contamination with the 

 manure or other discharges from the sick. 



(2) Preventive inoculation. — One of the most important discoveries 

 in connection with this disease was made by Louis Pasteur in 1881, 

 and consisted in the new principle of producing immunity by the 

 inoculation of weakened cultures of the bacillus causing the disease. 

 This method has been quite extensively adopted in France, and to 

 some extent in other European countries, and in the United States. 

 The fluid used for inoculation consists of bouillon in which modified 

 anthrax bacilli have multiplied and are present in large numbers. 

 The bacilli have been modified by heat so that they have lost to a 

 certain degree their original virulence. Two vaccines are prepared. 

 The first or weaker for the first inoculation is obtained by subjecting 

 the bacilli to the attenuating effects of heat for a longer period of time 

 than is the case with the second or stronger vaccine for a second 

 inoculation some twelve days later. 



These vaccines have been used for cattle and sheep. Their oower 

 to prevent a subsequent attack of anthrax has been the subject of 

 controversy ever since their use began. The French claim that the 

 vaccines are successful in protecting cattle and sheep and that the 

 losses from anthrax in France have been much reduced by their per- 

 sistent application. According to other observers there are several 

 difficulties inherent in the practical application of anthrax vaccina- 

 tion. Among these may be mentioned the variable degree of attenua- 

 tion of different tubes of the vaccine and the varying susceptibility 

 of the animals to be inoculated. Nevertheless, the use of this vac- 

 cine is increasing and has reduced the mortality in the affected dis- 

 tricts from an average of 10 per cent with sheep to less than 1 per 

 cent, and from 5 per cent with cattle to less than one-half of 1 per cent. 



It is very important to call attention to the possibility of distribut- 

 ing anthrax by this method of protective inoculation, since the bacilli 

 themselves are present in the culture liquid. It is true that they have 

 been modified and weakened by the process adopted by Pasteur, but 

 it is not impossible that such modified virus may regain ita original 

 virulence after it has been scattered broadcast by the inoculation of 



