THE NUCLEUS 



39 



it shows the same staining reactions as chromatin, or may be double, 

 consisting of an outer achromatic and an inner chromatic layer. Ac- 

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

 the linin-network. 



Interesting questions are raised by a comparison of these facts 

 with the conditions observed in some of the lowest organisms, such 

 as the flagellates and lower rhizopods among animals and the 



CO 



QQ 



Fig. 16. Forms of Cyanophyceae, Bacteria, and Flagellates showing the so-called scattered 

 or distributed nuclei. [A-C. BtJTSCHLl; D-F. SCHEWIAKOFF; G-J. CALKINS.] 



A. Oscillaria. B. Chromatium. C. Bacterium lineola. D. Achromatium. E. The same in 

 division. F, Fission of the granules. G. Tetramitus, with central sphere and scattered granules. 

 H. Aggregation of the granules. /. Division of the sphere. J. Fission of the cell. 



Cyanophyceae and Bacteria among plants. In many of these forms 

 (Fig. 1 6) no distinct nucleus can be demonstrated, the cell consisting 

 of a mass of protoplasm in which are scattered numerous deeply 

 staining granules. Many of these granules stain intensely with 

 haematoxylin and other "nuclear" dyes; like chromatin, they resist 

 the action of peptic digestion, and in at least one case (the bacterium- 

 like Achromatium, according to Schewiakoff, '93) they have the power 

 of division like the chromatin-granules of higher forms. For these 



