38 CELL DIVISION [CH. 



result from the coalescence of these vesicles, and its mem- 

 brane to be formed from their outer walls, much as a number 

 of small soap-bubbles may combine to form one large 

 bubble. It is more probable, however, that the membrane 

 is formed by some interaction between the substance of the 

 chromosomes and the surrounding cytoplasm, and is of the 

 nature of a precipitate which is re-dissolved when the nucleus 

 is again ready to divide. There are reasons, which will be 

 considered in a later chapter, for believing that at least the 



FIG. 4. Telophase of second maturation division of 

 the pollen of Tarts quadrifolia, after BOLLES LEE 

 (1912). The nuclear membrane is already formed 

 around the parts of the nuclei away from the 

 spindle, imperfect next to the spindle. The chromo- 

 somes are vaciiolated, attached by their ends to 

 the nuclear membrane, and connected with one 

 another by transverse branches. 



framework of the chromosomes persists in the "resting" 

 nucleus, and that they are in fact permanent entities which 

 remain from one cell-division to the next. That the mem- 

 brane is not always formed by the coalescence of vacuolated 

 chromosomes is shown by the fact that in the telophase of 

 mitosis the compact chromosomes may often be seen within 

 a large vesicular nucleus. 



Finally, before passing on to consider the nature of the 

 "achromatic spindle," there are a few points which can 

 conveniently be mentioned at this stage. These concern 



