136 MICEOBES, FERMENTS, AND MOULDS. 



These spores are much more tenacious of life than 

 the microbes themselves. The latter perish in a tempe- 

 rature of 60°, by desiccation, in a vacuum, in carbonic 

 acid, alcohol, and compressed oxygen. The spores 

 on the other hand, resist desiccation, so that they can 

 float in the air in the form of dust. They also resist 

 a temperature of from 90° to 95°, and the efiects of a 

 vacuum, of carbonic acid, of alcohol, and compressed 

 oxygen. 



In 1873, Pasteur, aided by Chamberland and Eoux, 

 carried on some experiments on a farm near Chartres, 

 in order to discover why this disease is so common in 

 some districts, in which its spread cannot be ascribed 

 to the bite of flies. Graas, on which the germs of 

 bacteridia had been placed, was given to the sheep. 

 A certain number of them died of splenic fever. The 

 glands and tissues of the back of the throat were 

 very much swelled, as if the inoculation had occurred 

 in the upper part of the alimentary canal, and by 

 means of slight wounds on the surface of the mucous 

 membrane of the mouth. In order to verify the fact, 

 the grass given to the sheep was mixed with thistles 

 and bearded ears of wheat and barley, or other prickly 

 matter, and in consequence the mortality was sensibly 

 increased. 



In cases of spontaneous disease it was surmised 

 that the germs which were artificially introduced into 

 food in the course of these experiments, are found 

 upon the grass, especially in the neighbourhood of 



