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TEXTBOOK OF ZOOLOGY 



cell division, more briefly mitosis, or indirect cell division. This 

 method of division was first described by Fleming in 1878, though 

 Schneider in 1873 described much of the complicated process. 



Although the process of mitosis is a continuous series of changes, 

 for convenience in stud3% these changes will be set out as six phases. 



CEL-l- 



MEfv»BRANE 

 CENTROSPHERE 

 tvlUCUEAR 

 MEMBRANE 



CHROMATIN 

 NUC!_EOI_US 

 CYTOPLASM 



SPINDL.E 



ASTRAU 



RAYS 



C H ROMOSO M E 



CENTBIOLE 



EARL-Y prophase: 



EQUATOR r Al_ 

 P1_ATE 



ASTER 



LATE PROPHASE 



MEXAPHASE 



ADJACENT 

 CEI_i_ 



INTER ZONAU 

 Fl BE RS 



EARLY ANAPHASE 



LATE ANAPHASE 



CL-EAVAQE 

 FURROW 



TELOPHASE 



DAUGHTER CELLS 



Figr. 22. — The stages in typical mitosis (indirect cell division) as .shown in 

 fertilized Ascaris eggs. They follow each other in order : resting cell, early pro- 

 phase, late prophase, metaphase, early anaphase, late anaphase, telophase, an'^ 

 daughter cells. (Drawn by Titus Evans.) 



Following the resting cell condition come the first changes, and the 

 early prophase condition is seen. In this stage the centriole has 

 divided, and the two pieces have moved considerably apart. The 



