SOMATIC CELL-DIVISION 



109 



nucleus as a whole may, however, show a change in orientation. ^ The 

 period between two rapidly succeeding mitoses is referred to as the 

 interphase. 



As a result of the mitotic process, the organization characterizing the 

 original nucleus is reproduced exactly in the two daughter nuclei. These 



Fig. 56. — Configurations often assumed by long chromosomes in anaphase. Spindle- 

 attachment regions indicated by dots. {After B'elar, 19296.) 



nuclei are structurally alike and have the same functional capacities. 

 When it is remembered that all of the nuclei of the body are produced by a 

 succession of such mitoses, it should be obvious that the equational char- 

 acter of the process is of the greatest importance with respect to problems 

 of metabolism, development, and heredity. 



Fig. 57. — Diagram of cytokinesis by cell-plate formation (first row) and by furrowing 



(second row). 



Cytokinesis. — The division of the cytosome is accomplished in a 

 variety of ways in different organisms (Fig. 57). A furrow may form at 

 the plasma membrane and gradually extend inward, cleaving the proto- 



2 See the discussion by Belaf (19296). 



