PHOSPHORIC ACID REQUIREMENTS OF YEAST. 199 



race of yeast. As pointed out by BEYEHINCK (XVIII.) and 

 others, yeast cells are rarely, if at all, present in the nectar of 

 flowers or natural honey ; consequently an artificial addition of 

 high-class yeast is really necessary for obtaining accelerated fer- 

 mentation, and will be the more successful inasmuch as its action 

 is barely interfered with by the relatively small proportion of 

 other fermentative organisms present. A few observations in 

 this connection have been made by E. CHUARD (I.), and more 

 exhaustive experiments by E. KAYSER and E. BOULLANGER (I.), 

 The latter workers also replaced the Gastine nutrient mixture 

 by simpler and equally efficient adjuncts, namely, by treating 

 i litre of diluted (24-27 per cent.) honey with either 1.5 c.c. 

 of maltopeptone and 1.5 grms. of potassium tartrate, or with 

 1.5 c.c. of maltopeptone and i grm. of ammonium tartrate; or 

 with o.i 2 grm. of spongy peptone, 1.5 grms. of potassium 

 tartrate and i grin, of ammonium phosphate. These workers 

 also conducted some experiments in connection with "oenomel," 

 a fermented mixture of honey and wine must. 



The opinion expressed by H. ELION (I.) as to the variable 

 jequirements of different yeasts in respect of phosphoric acid; 

 and the fluctuations in the resulting increase in fermentative 

 activity, still needs confirmation. 



L. LIEBERMANN (I.-III ) asserted that a portion of the 

 phosphoric acid present in the yeast cell is in the form of the 

 meta compound, and, in fact, the same as that contained in 

 nuclein ( 252), because he believed he had succeeded in iso- 

 lating barium metaphosphate both directly from yeast, and 

 also from the nucleic acid separated from yeast by himself and 

 B. VON BITTO (II.). The analyses advanced in support of this 

 view proved quite as untenable, under the criticism of KOSSEL 

 (IV.-VL), as was the case with the cognate characterisation of 

 nuclein as a mixture of the metaphosphates of xanthin and 

 allied bases with a proteid metaphosphate, and the resulting 

 inference that the artificial nucleins prepared in this way are 

 identical with certain natural nucleins. Nevertheless, the first 

 of these hypotheses has been found accurate, KOSSEL (V.) himself 

 having detected metaphosphoric acid among the decomposition 

 products of the nucleic acid of yeast (vol. ii. p. 161). Its occur- 

 rence was also demonstrated by ALB. ASCOLI (I. and II.) in the 

 molecule of plasmic acid, one of the derivatives of that acid. On 

 the other hand, no metaphosphoric acid has been detected in 

 other nuclein bodies, such, for instance, as the paranuclein 

 obtained by the action of pepsin on casein, and in the so- 

 called leuconuclein. 



Part of the phosphates or phosphoric acid consumed by yeast 

 is excreted from the latter in the form of phosphocarnic acid. 

 This interesting discovery, which, we are informed by B. HAAS 

 (II.), was made by J, Stoklasa, will, if found to be accurate, 



