42 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



radiation is absent from the protoplasm immediately 

 surrounding each centrosome, forming a clear field 

 called the attraction sphere. The lines that extend 



Cefllrosome 



tyindle 



wsomt 



e. 



Fig. 14. Diagram of mitosis. 



into the cytoplasm are known as polar rays. Those 

 that form the spindle seem to be attached to the 

 curved portions of the chromatin loops. 



2. Metaphase. This stage begins with the chro- 

 matin loops arranged radially in the equatorial plane 

 of the nucleus. The most important change in 

 mitosis now takes place, in that each chromosome 

 loop divides lengthwise to form two daughter chromo- 

 somes. This is an equal division, both qualitative 

 and quantitative. The curved portion of each 

 daughter loop passes along the rays of the achro- 

 matic spindle and approaches one or the other cen- 



