THE CELL. :)1 



pole to pole, and (c) the polar stria tioii which extends over the 

 whole cell with the exception of the part occupied by the 

 mantle fibres and the central spindle. The polar radiation 

 overlaps the equatorial zone in which the striations of the two 

 halves of the cell cross. 



At this period the metaphase begins by a longitudinal divi- 

 sion of the chromosomes, so that each mother thread is divided 

 into two daughter threads. If the chromosomes are in the form 

 of loops, the daughter loops begin first to separate from one 

 another at the curved apex and grow in opposite directions so as 

 to approach the poles. 



In this way there are formed from one mother star two 

 daughter stars (diaster) (Figs. 4,/, 9). Between the daughter 

 loops there extend connecting fibres which belong to the central 

 spindle. In this stage of the diaster we observe that the polar 

 striations no longer overlap the equatorial plane. 



Following this comes the constriction of the cell body in the 

 equatorial plane (Fig. 10). During the anaphase both daughter 

 stars become changed into coiled masses. In the coils the 

 typical structure of the resting nucleus again appears. 



The threads of the coil show again an irregular surface with 

 projections which join with one another. A nuclear membrane 

 is formed, and finally the framework of the resting nucleus is 

 built up, and the riucleolus appears. We notice that the ana- 

 phase is a reversal of the prophase. The last step in the 

 division is the complete separation of the cell into two halves. 

 During this separation the connecting fibres of the central 

 spindle become drawn together in the equator, and at the same 

 time there appear swellings in the fibres in this region. These 

 swellings approach one another more closely, and there is formed 

 between the daughter cells which are the product of the divi- 

 sion the so-called intermediate bodies (Zwischenkorper) (Figs. 11 

 and 13). The fibres radiating from the intermediate bodies soon 

 begin to be lost in the protoplasm, while the intermediate bodies 

 themselves often remain a much longer time. After the divi- 

 sion of the cell is completed the radiation disappears in most 

 cases. After the end of the real mitosis one may distinguish a 



