1 68 CHEMISTRY OF THE YEAST CELL. 



substitute from yeast ; that of K. Kleinschmidt (I.), and that 

 of Siebel. According to the hxtter, a pulp which he calls yeast 

 sugar and which has the appearance and consistence of con- 

 densed milk, is prepared by grinding pressed and de-bittered 

 beer yeast with sugar and starch. The preparation of concen- 

 trated fodder is the object of the methods of J. Steickel (I.) 

 and C. Brucker, as well as of the English Patent No. 20,060 

 of 1893. The purpose of several of the methods first-named 

 above is the recovery of a yeast extract to serve as a substitute 

 for meat extract ; and as a matter of fact some of the prepara- 

 tions of this kind already sold are undistinguishable by the laity 

 from real meat extract, so far as the smell, flavour, and external 

 appearance are concerned. Such are, e.(j. Bios, Eurostose and 

 Carnos, according to A. Eichexgruen (I.); and, according to 

 Lebbin (II.), Ovos as well. An intelligent manufacturer should 

 obviate all chance of such confusion by giving his yeast pre- 

 paration a special and indubitable title, e.g. Vegetable Peptone. 

 This, however, is not always the case, and it would appear that 

 <i fraudulent intention is not invariably absent. The foregoing 

 explanations may perhaps divert into a new channel the method 

 of testing adopted by foodstuff chemists for the detection of 

 this yeast extract. By means of the reagents employed in the 

 manufacturing process, and partly also as a residt of auto- 

 fermentation, the nucleins of the yeast suffer a more or less 

 extensive degradation, nuclein bases being liberated. Of the 

 latter, adenin and guanin are found in yeast, and consequently 

 occur in comparatively large amount in the yeast extract. On 

 the other hand, as has been shown by A. Kossel (X. and XL), 

 true meat extract contains little or none of these substances, 

 and is thereby distinguishable from such substitutes. The 

 provision of accurate and reliable data, in this respect is reserved 

 for future research in the wide field of the chemistry of the 

 yeast cell. 



§ 253.— Gly cog-en and Fat. 



One of the chief phenomena in the metabolism of higher 

 animals is the formation of sugar in the liver. The substance 

 of which this sugar consists was first observed by Claude 

 Beiinard (I.) in 1855, and recognised two yearns later, under 

 the name " mati^^re glycogene," as a carbohydrate similar to 

 vegetable starch (amylum), dissolving in water to furnish a 

 peculiar opalescent liquid, precipitable by strong alcohol, and 

 giving a brownish-red stain with iodine solution (iodine 2 grams, 

 potassium iodide 6 grams, and water 120). The occurrence of 

 such a colour reaction had been observed four years earlier by 

 R. L. TuLASNE (I.) in the young asci of truffles, and a few years 

 later (IL) on those of Erysiphe Aceris De CtmdoUe, a species of 



