OTHEE DISEASES OF DOMESTIC ANIMALS. 145 



duced by a microbe, with which Pasteur was able to 

 inoculate other animals (rabbits) ; for this purpose 

 he made use of the serous discharge from the horses' 

 nostrils. The inoculated rabbits died with all the 

 symptoms and lesions characteristic of the disease. 



The attenuation of this microbe by culture is 

 difficult, since at the end of a certain time the action 

 of the air kills it. Pasteur has, however, found an 

 expedient by which to accomplish his purpose. When 

 ttie culture is shown to be sterile in consequence of 

 the death of the microbe, he takes as the mother 

 culture of a fresh series of daily cultures the one which 

 was made on the day preceding the death of the first 

 mother culture. In this way he has obtained an 

 attenuated virus with which to inoculate rabbits, and 

 the same result might undoubtedly be obtained in 

 the case of horses. 



There are many other contagious diseases which 

 afiect domestic animals, and which are probably due to 

 microbes, such as, for instance, the infectious pneumonia 

 of horned cattle. This was probably the first disease in 

 which the protective effects of inoculation were tried 

 according to Wilhelm's method. This method consisted 

 in making an incision under the animal's tail with a 

 scalpel dipped in the purulent mucus or blood taken 

 from the lung of a beast which had died of pneumonia ; 

 sometimes the serous discharge from the swelling under 

 the tail of an Inoculated animal was used for others. 

 Fever and loss of appetite ensued, lasting from eight 



