2i 4 ORGANIC FOODSTUFFS. 



0.008 per cent, of proteid nitrogen) was absorbed by the yeast. 

 WAHL and HANTKE (I.) found the relative proportions of nitrogen 

 absorbed (from wort) by the yeast, in the form of proteins, pep- 

 tone and amides, were: 0.4: 1.7: 19.9 mgrms. respectively per 

 1000 c.c,, the initial content in the wort being 9.0 : 27.4 : 52.0. In 

 this case also amides were preferentially absorbed. Though P. 

 PETIT and G. LABOURASSE (I.) consider that their observations 

 justify an opposite conclusion, it follows from R. KUSSEROW'S (IV.) 

 experiments that the protein degradation products are better 

 foodstuffs than the unaltered proteins. This partly explains the 

 favourable influence of an addition of malt culms to the mash, 

 especially in cases of sluggish fermentation of rich mashes. This 

 throws new light on the influence of the kind of mashing process 

 on the protein content of beer wort, and thereby on the progress of 

 the development of yeast, as also the course of fermentation and the 

 character of the resulting beer, especially in contrasting the two 

 opposite processes of the infusion method on the one hand and the 

 Bavarian thick-mash method on the other. ADALBERT FLUHLER 

 (I.) was the first to draw attention to this, and his work was con- 

 tinued by V. GRIESSMAYER (II.). C. J. LINTNER (Y.) reported 

 that these discoveries were confirmed by Ad. Ott. 



HAYDUCK (IV.) carried out the first experiments worthy of 

 mention on the ratio between the size of the yeast crop and the 

 amount of the nitrogen content in the nutrient medium ; and 

 this worker found that asparagin, when present as the sole source 

 of nitrogen, and to an extent not exceeding 0.25 per cent., in a 

 saccharified solution of mineral salts, was completely absorbed by 

 the added pressed yeast. With a larger quantity of asparagin 

 present, more was consumed, but in all cases a portion remained 

 undecomposed. On the other hand, A. L. STERN (I. and III.) 

 found 0.025 P er cen t. of asparagin to be the maximum, no appre- 

 ciable increase in the reproduction of the cells occurring with any 

 larger quantity. A similar observation was made by P. THOMAS 

 (I.) with regard to urea as a source of nitrogen. IWANOWSKI (II.) 

 states that the degree of alcoholic fermentation in a saccharified 

 mineral-salt solution varies inversely with the amount of peptone 

 added as the source of nitrogen. On the other hand, in experi- 

 ments with wine must containing i per cent, of added peptone, 

 J. BEHRENS (XIII.) found that this addition assisted fermentation 

 (by pure yeast). 



The observations of D. DELBRUCK (IV.), CES. FORTI (L) and 

 E. BOULLANGER (I.) show that the quantity of nitrogen absorbed 

 from the nutrient medium is primarily dependent on the species 

 of yeast employed. It also varies, however, with one and the 

 same yeast, according to the other conditions of environment, 

 being greater, for instance, in aerated and strongly agitated cul- 

 tures. This was noted both by the last-named worker and also 

 by 0. F. HYDE (I.) who found that 23.8 per cent, of the nitrogen 



