CHAPTER XLVIII. 



CHEMISTRY OF THE YEAST CELL. 



§ 252.— Chemistry of the Yeast Cell Nucleus. 



Recent investigations have shown the probability that, in place 

 of being in a free state in the cell, the alttuminoids present form 

 part of more highly constituted bodies termed proteids. At a 

 given moment these bodies are split up into the albuminous 

 nuclevis on the one hand, and the adherent lateral chains on the 

 other. These latter have been termed prosthetic groups by A. 

 KossEL (V.), and explained as the real means by which the vital 

 activity of the cell is enabled to act. Of the groups into which 

 the proteids themselves have been classified, one, namely that 

 of the nucleins, is of particular importance, since, as the name 

 itself implies, it furnishes important structural material for the 

 nucleus. A little fuller information on this point will probably 

 be not unwelcome to the reader, and for this reason a few 

 remarks concerning certain conclusions of a practical nature will 

 now be given. 



In 1S69 F. MiESCHER (I.) isolated, from the nuclei of pus 

 cells, a nitrogenous constituent to which he gave the name 

 nuclein. This body differed from other proteids, both as regards 

 its percentage of phosphoi'us and by its power of withstanding 

 pepsine. The occurrence of such nuclein in yeast cells was then 

 discovered by F. Hoppe-Seyler (IV.). After doubt had been 

 cast by N^geli and LoEW (II.) on the accuracy of these obser- 

 vations, A. KossEL (III.) succeeded in obtaining considerable 

 quantities of fairly pure nuclein from pressed yeast. For this 

 purpose the yeast, stirred to a pulp, was left for several hours 

 under water, the latter being renewed once or twice in the 

 interim. The yeast sediment was then introduced into dilute 

 cau.stic soda, which extracted the nuclein. As, however, the 

 latter was at the same time gradually attacked by the solvent, 

 it was found desirable to place the mixture at once on a number 

 of filters and to allow the filtrate to di-op into dilute hydro- 

 chloric acid, which re-precipitated the dissolved nuclein. The 

 precipitates were then united on a filter, washed with dilute 

 hydrochloric acid and alcohol, and repeatedly extracted with the 

 same, thus furnishing a product which, when dried under the 



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