240 



SOME ASPECTS OF CELL-CHEMISTRY AND CELL-PHYSIOLOGY 



The distribution of these substances throughout the cell varies 

 greatly not only in different cells, but at different periods in the life 

 of the same cell. The cardinal fact always, however, remains, that 

 there is a definite and constant contrast between widens and cytoplasm. 

 The latter always contains large quantities of nucleo-albumins, certain 

 globulins, and sometimes small quantities of albumins and peptones ; 

 the former contains, in addition to these, unclein and nncleo-firoteids, 

 which as the names indicate, forms its main bulk and its most con- 

 stant and characteristic feature. It is the remarkable substance, 

 nuclein,— which is almost certainly identical with chromatin, — that 

 chiefly claims our attention here on account of the physiological role 

 of the nucleus. 



2. The Nnclein Series 



Nuclein was first isolated and named by Miescher in 1871, by 

 subjecting cells to artificial gastric digestion. The cytoplasm is 

 thus digested, leaving only the nuclei; and in some cases, for m- 

 stance pus-cells and spermatozoa, it is possible by this method to 

 procure large quantities of nuclear substance for accurate quanti- 

 tative analysis. The results of analysis show it to be a complex 

 albuminoid substance, rich in phosphorus, for which Miescher gave 

 the chemical formula C.gH^gN.PgO.^^. Later analyses gave some- 

 what discordant results, as appears in the following table of per- 

 centage-compositions : ^ — 



C 

 H 

 N 

 P 



PrS-CELLS. 



(Hoi>pe-Seyler.) 



49.58 



7.10 

 15.02 



2.28 



Spermatozoa of Salmon. 

 (Miescher.) 



36.11 



5-15 

 13.09 



5-59 



Human Brain. 



(v. Jaksch.) 



50.6 

 7.6 



13.18 

 1.89 



These differences led to the opinion, first expressed by Hoppe- 

 Seyler, and confirmed by later investigations, that there are several 

 varieties of nuclein which form a group having certain characters 

 in common. Altmann ('89) opened the way to an understanding 

 of the matter by showing that "nuclein" may be split up into two 

 substances; namely, (i) an organic acid rich in phosphorus, to which 

 he gave the name nucleic acid, and (2) a form of albumin. Moreover, 



1 From Halliburton, '91, p. 203. [The oxygen-percentage is omittea in this table.] 



