CELL DIVISION 



briefly as follows: In the beginning of this phenomenon, the 

 nucleus, which plays the most important role, grows larger. 

 Its chromatin greatly increases and becomes contorted so as to 

 form a dense convolution, the close skein, or spireme. Then 

 the chromatin fibrils further thicken, become less convoluted 

 and form irregularly arranged loops, the loose skein. During 



Close Skein Mother stars 



(viewed from the Loose Skein (viewed from 



side) ; Polar field, (viewed from above i. e., from the the side). 



pole). 



Mother Star Daughter Star 

 (viewed from above). 









Beginning. Completed. 



Division of the Protoplasm. 



FIG. 2. Karyokinetic figures observed in the epithelium of the oral cavity 

 of a salamander. 



The picture in the upper right-hand corner is from a section through a dividing 

 egg of Siredon pisciformis. Neither the centrospmes nor the first stages of the de- 

 velopment of the spindle can be seen by this magnification. X 560. (From Brubaker.} 



the formation of these skeins the nuclear membrane and the 

 nucleoli disappear. The fibrils of the loose skein now separate 

 at their peripheral turns into a score of loops, the closed ends of 

 which point toward a common center a clear space called the 

 polar field. When seen from above these loops of chromatin 

 make a wreath, called the mother wreath; when seen from the 



