INORGANIC ACIDS AND SALTS. 243 



Methyl-A. Ethyl-A. Fropyl-A. Butyl-A. 

 Kegnard 20 15 10 2.5 



Yabe . . 



Isobutyl-A. Amyl-A. Hexyl-A. Capryl-A. 

 Regnard . i.o 0.2 o.i 



Yabe . . 3.0 i.o 0.5 



Hence the toxic properties of these alcohols increase with the 

 number of carbon atoms in the molecule. 



269. Inorganic Acids and Salts. 



Though several observations have been published already with 

 regard to the influence of carbon dioxide on the yeast cell, the 

 importance of this hitherto imperfectly appreciated question 

 to fermentation technology renders further investigation highly 

 desirable. On repeating in 1887 the experiments first performed 

 by C. PRANDTL (I.) in 1865 on the cultivation of beer yeast in 

 open and sealed tubes respectively, G. FOTH (I.) observed a smaller 

 increase of the sowing under the latter conditions ; but it is 

 doubtful in how far this is due to the presence of carbon dioxide 

 or to the lack of oxygen. After L. LINDET (III.) had made 

 further experiments, in 1889, without any decisive result, H. 

 ORTLOFF (I.) in 1900 recorded a similar adverse effect on repro- 

 duction in pure cultures of Sacch. cerevisice /., Hansen, Sacch. 

 Pastorianus /., //., ///., Sacch. ellipsoideus /.and II., Saaz yeast, 

 Frohberg yeast and Logos yeast, traversed by a current of 

 (presumably oxygen-free) carbon dioxide throughout the whole 

 period of reproduction. With regard to wine yeasts, H. MULLER- 

 THURGAU (II. and III.) had already shown in 1889 that repro- 

 duction was checked by a high content of carbon dioxide in the 

 wine freshly inoculated with that yeast. In the experiments of 

 LOPRIORE (II.) with the cells of a hanging-drop culture of pure 

 yeast, it was found that budding continued in a few cells during 

 the first 4-6 hours of passing oxygen-free carbon dioxide through 

 the Bottcher cell, but not afterwards. The divergent sensitive- 

 ness of the various species and races had already been observed 

 by FOTH (II.), who found Sacch. Pastorianus I. to be more resistant 

 than Carlsburg bottom yeast No. i ; and this divergence is also 

 deducible from OrtlofFs results. A high percentage of the gas in 

 question also diminishes the fermentative activity, judged as a 

 whole, in the culture, this being confirmed by both Foth and 

 Ortloff. As pointed out, however, by E. C. HANSEN (XXXVI.) 

 and J. C. HOLM (I.), such a result admits of two opposite interpre- 

 tations ; for though the yield of alcohol per cell of yeast crop may 

 work out lower in the cultures treated with carbon dioxide, and 

 thus lead to the conclusion that an adverse influence has been 

 exerted by that gas, the exact opposite may have occurred in 



