SOCIETY OF NORTHERN ILLINOIS. 199 



THE YEAST PLANT. 



[Saccharomyces Cirevisx. 



BY MRS. DR. HARRIS, OF GALENA. 



To the Horticultanil Soc'u'tij of Northern Illinois: 



We have no intention, in the present writing, of wading very 

 far into the deep waters of bacteria and Pasteur's germ-theory of 

 disease; nor do we purpose to take sides with either genu-theorists 

 or anti-germ-theorists of the medical fraternity; neither do we desire 

 to press upon your attention a nuitter that is far-fetched or of little 

 practical utility. 



The Yeast Plant, it is well known, is at present understood to 

 be the natural and legitimate pareiit of rinout; fi'rniinitatio)i — that 

 chemical process which represents the first stage of "spoiling" of 

 fruits that are canned, or otherwise preserved or conserved, with or 

 without cooking. This "little giant " is the groat factor upon which 

 the brewer, the distiller, and the wine-maker depend for tiieir stuck 

 in trade. Without its agency beer would not be fermented, alcohol 

 would not be alcohol, nor would wine be produced from the juice of 

 the "■rape. (Suppose we turn it over as an offender to the W. (\ 

 T. U."s.) 



To the horticulturist, at least to him who depends upon canning 

 his garden products for market, this tiny organism is of very great 

 importance, not as a friend, but as a foe. Since fruit and vegetable 

 canning is rapidly growing into an immense industry, one by means 

 of which we Americans are aiming to supply the world with the 

 perishable products of our soil, products which, but for said canning 

 process, would be left largely to waste upon our hands, those micro- 

 cosms which inHuence said process and affects the quality of the 

 goods in question, compel us to treat them with respect. Under 

 these consideniti(ms we have thought that a brief, though rude, 

 sketch of the present status of the yeast plant in science and prac- 

 tice might not be deemed uninteresting. 



Ever so many years ago chemists were greatly puzzled to uiuler- 

 stand xi)ont<(n('<)iix ffrincnfafion. viz: to know why the carbon and 

 hydrogen and oxygen of sugar (particularly grape sugar) should, of 

 their own free will, when moisture and a suitable temperature were 

 present, get up a commotion evolving gas and heat, and presently 

 rearrange themselves into a difl"en>nt combination, forming an en- 

 tirely new snbstance. (i/cnliol, which latter suljstancc. upon analysis, 

 was found to contain the same chemical elements in the same quan- 

 tity and proportion (or very nearly so) as did the original sugar. In 

 honielv ))hrase. they were s\iffering to know what set the luachine 

 in motion. 



In 1680 a German ''with a terrible name which noliody could 

 spell."" etc.. introduced the microscope into the discussion of this 



