1 66 CHEMISTEY OF THE YEAST CELL. 



and Methyl Blue (or Methyl Green), but red by a mixture 

 of Safranine and Pale Green. Such behaviour having been 

 macrochemically observed with the known dyestuffs, the same 

 can also be employed microchemically for examining the cell for 

 the presence of one or another chemical substance occurring 

 in local accumulations therein. In any event, care is necessary 

 in the preliminary treatment of the preparation, since in many 

 cases this has a decisive influence on the results. For more 

 detailed information on this point the reader is referred to the 

 monograph by A. Zimmermann (II.). In so far as these micro- 

 chemical reactions enable a reliable decision to be formed, it has 

 been shown in this manner that the nucleus of the yeast cell is 

 rich in nuclein, and that the latter is probably not present in 

 the cytoplasm. Now, as already shown in §250, the nucleus 

 consists of the reticulated framework, the sap (or juice), the 

 membrane, and the nucleoli. The first-named, in tiu'n, is com- 

 posed of the reticulated matter known as linin, which is difficult 

 to stain, and of the globules situated at the intersections of the 

 network, these globules consisting of a substance which is 

 readily penetrated by dyestuffs, and which has therefore received 

 the name chromatin (§ 35). The nuclein is located in this 

 chromatin, whereas the filaments of linin and the nucleoli con- 

 tain, in addition to albumin, a substance termed plastin, which 

 differs appreciably from, although closely allied to, the nucleins. 

 The question as to the amount and nature of the other 

 nitrogenous substances associated with the nucleoproteids in 

 the nucleus of the yeast cell, cannot at present be satisfactorily 

 decided, the reports on this matter being few in number and 

 not reliable. The same applies to the nitrogenous constituents 

 of the cytoplasm (§ 2 1 9), the scanty communications referring 

 to which will be dealt with in § 255. 



The composition of the yeast water prepared in the manner 

 described in § 82 will be briefly considered here from the 

 standpoint of the reports mentioned in the foregoing para- 

 graphs. Even mere boiling in water is sufficient to break up 

 the yeast nuclein, with formation of nuclein bases and free 

 phosphoric acid, which therefore occur as constituents of yeast 

 water. The appearance of phosphoric acid in decoctions of 

 yeast had already been observed by A. Biechamp (VII.), who 

 found, in 1865, that 100 grams of dry yeast lost, on extraction, 

 2.8 to 3 grams of phosphoric acid, part of which was in the 

 free state. This was confirmed by A. Kossel (III.). He also 

 found that this liberation proceeds rapidly at first, but later on 

 very slowly. With regard to the extraction of nitrogenous sub- 

 stances (xanthin, guanin, sarcin, carnin, levicin, and tyrosin) 

 from yeast cells by the water in which they have been boiled, 

 certain experiments were made in 1874 by P. Schuetzenberger 

 (I.), who, by repeatedly extracting yeast with boiling water 



