CHAPTER VIII 

 Microphytology 



THIS, the youngest of the sciences, already occupies 

 almost as much space in the laboratories of the world as 

 either of her elder sisters. So young is she that it is doubt- 

 ful whether her parents have definitely agreed upon a 

 name as yet. Botanists, pathologists, chemists are anxious 

 to stand as sponsors ; while brewers, dairymen, indigo and 

 tobacco manufacturers and other wealthy men of commerce 

 are quite willing to act as godfathers if the men of science 

 will consent to stand aside. 



The science dates its birth from Pasteur's researches 

 upon fermentation. Pasteur proved that fermentation is 

 not a chemical action in the ordinary sense, but the work 

 of living cells which, in taking from sugar the oxygen 

 needed for their respiration, make such an alteration in its 

 molecule as causes it to break up into alcohol and carbonic 

 acid. The amount of sugar which they consume as food is 

 insignificant as compared with the amount which, by their 

 vital activity, is decomposed. It is these bye-actions 

 which characterize minute organisms. They not merely 

 consume a certain amount of -the medium in which they 

 live and obtain oxygen for its combustion from the air, as 

 a larger plant or an animal would do, but they profoundly 

 alter the constitution of the rest. For every ounce which 

 yeast adds to its own weight when growing in a solution of 

 sugar, it decomposes about 20 ounces into alcohol and car- 

 bonic acid. There are certain minute animals the number 



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