L 



BOTTOM YEASTS. 117 



foniR'i- leasuii alone woiiUl pii'tlude the expedjiiic-y of perfect 

 refjulaiity in the cells of a culture. Moreover, owing to the 

 iiii])erfectstjite of our knowledge, both in cheuiistry iinil physics, 

 the production of ahsohitely identical conditions of existence in 

 two cultures started at diil'fient times, is unattiiinahle. Again, 

 even when working with a single cell, it will be found tluit the 

 daughter-cells, grown in one and the sjinie nutrient medium, 

 • lifVer among themselves; in one of them one of the inheriteil 

 properties latent in the m(jther-cell makes its appejinmce, whil>t 

 ill another of the cells other inherited properties prepondeinte. 





i 





^ 1 



Fic!. 129. — Sacch. Pastoriamis I. Hansen. 

 Cells from the st'dlmental yeast o( a young culture in beer wort. Magii. ic^o. (Aftfr 



It is nccessjiry t<i lay emphasis on this p(^int, because it onlv too 

 often happens that a beginner in the cultivation of yeast feels 

 compelled to lose all faith in his kiutwledge when he ob.serves 

 that a ])ure culture, prepared from a single cell strictly according 

 to all the rules of the method, consists of cells all more or less 

 tlitVerent in size and form. Now there is nothing special about 

 such variability, which is exhibited liy l>acteria and all other 

 living organisms, ami that too in no less a degi ee than with 

 the yeasts. Xeverthele.s.s, within the limits alVoideil bv the 

 aforesaid ditiiculty of control, one an<l the sjinie species grown 

 under the sjime conditions will give cells of aj>proximatelv luii- 

 form shape, s;iy, for instance, that of the .sediment;tl veust of 

 the L'erevisia' type. 



That under these conditions, it is actually jnissible to trace 

 dilVerontial characteristics, may be explained by the aid of the 

 two drawings shown below, both of tliem representing sjvmples 

 from the sediment;il ywist of a culture in beer wort, at the clo.se 

 of tlie primary fermentation. Fig. 130 is the so-called Ciuds- 



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