24 PASTEUR'S WORK 



Space permits only a brief and incomplete statement of the work 

 of Pasteur, and in doing this the chronological order will not be fol- 

 lowed. He overthrew the doctrine of spontaneous generation. 

 Although Harvey, two centuries earlier, had laid down the dictum, 

 omne vivum ex vivo, there were those who held that this does not 

 hold for the lowest forms of life. As Abel says, "Homer wrote of 

 autochthonus men who sprang from the soil; the sixteenth century 

 saw recipes for the manufacture of mice and frogs, and in later days, 

 it was claimed that lower forms of animal life must have developed 

 spontaneously because the Bible makes no mention of their having 

 been taken into the ark by Noah." It was essential to the development 

 of bacteriology, which depends so largely on sterilization, to dispose 

 of spontaneous generation and to show that lower, as well as higher, 

 forms of life breed true. This Pasteur did with the aid of Tyndall, 

 and others. He showed that fermentation is due to the growth of 

 living organisms, and that each kind of fermentation, like that in 

 beer, wine and milk, is due to specific organisms. Furthermore he 

 showed that a temperature high enough to kill these organisms arrests 

 fermentation. By this process, now known as pasteurization, he pre- 

 served beer, wine and milk. Among this line he went further still 

 and demonstrated that putrefaction, like fermentation, is due to bac- 

 terial growth. Lister utilized this discovery in the development of 

 antiseptic surgery from which aseptic surgery has come. If each 

 kind of fermentation has its specific organism, why may not each dis- 

 ease have its specific bacterial cause? Exposure to smallpox does not 

 develop typhoid fever. The answer to this question has been given by 

 the discovery of the specific causal agents of many diseases, and 

 when found and tested, their specificity is demonstrated. The anthrax 

 bacillus grown through a hundred generations and then inoculated 

 into susceptible animals induces anthrax still. Pasteur found that 

 certain specific bacteria can be so attenuated by unfavorable condi- 

 tions of growth that they will not develop the disease in susceptible 

 animals, but do impart to them immunity to infection with virulent 

 strains. In this way he prepared vaccines for chicken cholera, swine 

 eryripelas and anthrax. He also developed the successful treatment of 

 hydrophobia, now used in every part of the world. 



