28 GENERAL SKETCH OF THE CELL 



the term "linin." Both forms of granules occur in the chromatic 

 network, while the achromatic network contains only oxychromatin. 

 They are sharply differentiated by dyes, the basichromatin being 

 coloured by the basic anilines (methyl green, saffranin, etc.) and other 

 true "nuclear stains"; while the oxychromatin-granules, like many 

 cytoplasmic structures, and like the substance of true nucleoli (pyrenin), 

 are coloured by acid anilines (rubin, eosin, etc.) and other "plasma 

 stains." This distinction, as will appear in Chapter VII., is probably 

 one of great physiological significance. 



Still other forms of granules have been distinguished in the nucleus 

 by Reinke ('94) and Schloter ('94). Of these the most important 

 are the " oedematin-granules," which according to the first of these 

 authors form the principal mass of the ground-substance or "nuclear 

 sap " of Hertwig and other authors. These granules are identified 

 by both observers with the " cyanophilous granules," which Altmann 

 regarded as the essential elements of the nucleus. It is at present 

 impossible to give a consistent interpretation of the morphological 

 value and physiological relations of these various forms of granules. 

 The most that can be said is that the basichromatin-granules are 

 probably normal structures; that they play a principal role in the 

 life of the nucleus ; that the oxychromatin-granules are nearly related 

 to them ; and that not improbably the one form may be transformed 

 into the other in the manner suggested in Chapter VII. 



The nuclear membrane is not yet thoroughly understood, and 

 much discussion has been devoted to the question of its origin and 

 structure. The most probable view is that long since advocated by 

 Klein ('78) and Van Beneden ('83) that the membrane arises as a 

 condensation of the general protoplasmic reticulum, and is part of 

 the same structure as the linin-network and the cyto-reticulum. Like 

 these, it is in some cases "achromatic," but in other cases it shows 

 the same staining reactions as chromatin, or may be double, con- 

 sisting of an outer achromatic and an inner chromatic layer. _ Ac- 

 cording to Reinke, it consists of oxychromatin-granules like those of 

 the linin-network. 



3. Chemistry of the Nucleus 



The chemical nature of the various nuclear elements will be considered in 

 Chapter VII., and a brief statement will here suffice. The following classification 

 of the nuclear substances, proposed by Schwarz in 1887. has been widely accepted, 

 though open to criticism on various grounds. 



1. CJiroDiatin. The chromatic substance (basichromatin) of the network and of 



tliose nucleoli known as net-knots or karyosomes. 



2. Li)ii)i. The achromatic network and the spindle-fibres arising from it. 



