INTRODUCTION. 2$ 



other matter in which the elements are connected by a 

 very feeble affinity. 



Pasteur was the first to declare and prove that fermen- 

 tation is an ordinary chemic transformation of certain 

 substances, taking place as the result of the action of 

 living cells, and that the capacity to produce it resides in 

 all animal and vegetable cells, though in varying degree. 



In 1862, he published a paper "On the Organized 

 Corpuscles existing in the Atmosphere," in which he 

 showed that many of the floating particles which he 

 had been able to collect from the atmosphere of his 

 laboratory were organized bodies. If these were planted 

 in sterile infusions, abundant crops of micro-organisms 

 were obtainable. By the use of more refined methods 

 he repeated the experiments of others, and showed clearly 

 that "the cause which communicated life to his infu- 

 sions came from the air, but was not evenly distributed 

 through it." 



Three years later he showed that the organized cor- 

 puscles which he had found in the air were the spores or 

 seeds of minute plants, and that many of them possessed 

 the property of withstanding the temperature of boiling 

 water — a property which explained the peculiar results 

 of many previous experimenters, who failed to prevent 

 the development of life in boiled liquids enclosed in 

 hermetically-sealed flasks. 



Chevreul and Pasteur (about 1836) proved that animal 

 solids did not putrefy or decompose if kept free from 

 the access of germs, and thus suggested to surgeons that 

 the putrefaction which occurred in wounds was due rather 

 to the entrance of something from without than to some 

 change within. The deadly nature of the discharges 

 from these wounds had been shown in a rough manner 

 by Gaspard as early as 1822 by injecting some of the 

 material into the veins of animals. 



