20 MICROBES AXD HEALTH. 



In bread baking in London, alone, in the year 1858, 

 it was estimated that over three hundred thousand gal- 

 lons of alcohol were evolved and lost. 



Some restrict and confine fermentation to the de- 

 composition of non-proteid substances; i. e., those not 

 containing albumen. Starch and sugar are examples. 

 These differ from grain and flour as they have no power 

 within themselves to undergo change, but must be in- 

 fluenced by another substance, and this other substance 

 is called a ferment. Yeast, already mentioned, is an 

 example of ferment with which all are familiar. 

 Yeast was employed as "leaven" as early as the year 

 1892 B. C. The absence of yeast or leaven constituted 

 the peculiarity of the bread used at the passover, B. C. 

 1491. Yeast is composed of living organisms in the 

 form of little cells or germs, about one three-thou- 

 sandth of an inch in diameter. They are germs just 

 as much as the so called germs found in disease. Both 

 are vegetable organisms and under the proper condi- 

 tions of heat and moisture manifest life and produce 

 fermentation. 



The tissue-change going on in the human body, re- 

 pair and waste, is a process of fermentation, and is 

 carried on through the influence of the little germ cells 

 of which the body is formed. It is sometimes called 

 oxidation, because the red blood-corpuscles or cells 

 which float in the blood-stream in great numbers, in 

 their passage through the lungs, absorb oxygen from 

 the air we breathe, and through the circulation it is 

 carried to all parts of the body, and absorbed by the 

 cells, which constitute the different organs and tissues. 



