260 Causes and Course of Organic Evolution 



effected the nucleolus becomes, as described by the writer 

 (103: 207), the seat of two opposing forces or lines of energy, 

 that cause separation of its substance into two daughter nucle- 

 oli. But that there is an intimate energizing and morphological 

 connection between the nucleolus — even in its modification 

 into chromosomes — and the peripheral protoplasm of the cell 

 is demonstrated by the early appearance in the latter, and 

 contemporaneously with the above nucleolar changes, of scat- 

 tered microsomata that gradually come together to aid in 

 formation of the future cell wall. 



Meanwhile the daughter nucleoli retreat from each other, 

 as if they had become the centers of opi)osing and radiating 

 forces, which cause them as they retreat to drive apart the 

 surrounding nuclear chromatin threads and associated nucleo- 

 plasm. The substance of the latter passes through clearly 

 visible pores or areas in the nuclear membrane, and in time 

 aggregates outside the nuclear membrane. Soon thereafter 

 the chromatin of the membrane, that is in contact ^dth these 

 masses, begins to break down and fuses with them, at the same 

 time that both masses seem to get driven apart by radial 

 lines of repellent energy passing out from the daughter nucleoli. 

 At length these last reach and embed themselves in the chro- 

 matin-nucleoplasmic masses, that then become astral radiant 

 centers from which chromatin threads radiate out. The most 

 distant sets of these represent the original radial chromatin 

 threads of the cell, that pass from the nucleus to the pyrenoids 

 of the peripheral protoplasm, but the inner and nearer to each 

 other form at first threads in the nuclear spindle, that for a 

 time connects the daughter nuclei. 



A stage is thus reached when a balanced adjustment seems 

 to be effected between this chromatin force or cognitic energy, 

 and some neutralizing or counteracting force. Meanwhile a 

 beautiful nuclear spindle, in part constructed of chromatin- 

 linin threads, in part of protoplasmic substance, has resulted 

 from the nuclear- and nucleolar-derived chromatin threads 

 that radiated outwardly. By the activity of this spindle, and 

 in part of the peripheral protoplasmic layer, microsomata aggre- 

 gate which later aid in formation of the cross i^artition-wall. 



In describing the above succession of events, the Avriter 

 wrote (103: 207) that "the nucleolus is now the center of two 

 opposing forces, acting along the long axis of the cell; in fact 

 that from this i>oint onward the nucleolus jjresides over, guides, 

 and impels the movements of the nucleus," and again, refer- 



