GROWTH OF THE YEAST PLANT 



119 



With regard to the influence of sugar, there is, according 

 to Slator, a proportion between the size of the crop and the 

 initial concentration of glucose up to about I per cent. The 

 accompanying curve (Fig. 1 1) shows the retarding influence of 

 sugar in increasing concentration, when sugar is the limiting 

 factor. Its slope corresponds to 3900 x io 16 cells per gm., 

 a figure in fair agreement with the calculated number. 



With respect to alcohol, under ordinary conditions of 

 brewing its accumulation is never so great as to be a significant 

 factor in the growth of the yeast ; if, however, alcohol be present 



=60 



o 



UD 



03 



5 1-0 1-5 2-0 25 

 Cms. Glucose per 100 cc. 



FIG. ii. 



in excessive amount, it has a limiting action ; thus the presence 

 of 8 per cent of alcohol in the fermenting liquor may inhibit 

 reproduction, especially if the supply of oxygen is limited. 



This survey, incomplete though it be, shows the usefulness 

 of offspring as an index of growth * and emphasizes the im- 

 portance of various conditioning factors in the governance of 

 life processes. 



The growth rate of a plant varies with the age of the 

 organism and also may show periodic and seasonal variation. 



* A little thought will show that measurements of increase in length and girth 

 of those parts of plants exhibiting merismatic activity are in reality measurements 

 of offspring of the dividing elements. 



