8 



ELEM-ENTS OF HISTOLOGY. 



[Chap. I. 



process of the karyokinesis is represented in the ad- 

 joining figure, 5, and it consists of the following phases : 

 (a) The nuclear network become very pronounced, 

 while the nuclear membrane disappears, and the 

 fibrils of the nuclear network becomes twisted and 

 bent into a more or less dense convolution; at the 

 same time the nucleus, as a whole, is considerably 

 enlarged, (b) The fibrils unravel into loops, arranged 



Fig. 5. Karyokinesis. 



A, Ordinary nucleus of a columnar epithelial cell ; B, c, the same nucleus in the 

 stage of convolution ; D, the wreath, or rosette form ; E, the aster* or single 

 star ; p, a nuclear spindle from the Descemet's endothelium of the frog's 

 cornea; G, H, I, diaster; K, two daughter nuclei. 



around the centre as a wreath or rosette, (c) The 

 peripheral points of the loops become broken, and 

 we obtain a star-shaped figure of single loops the 

 aster, (d) The loops separate into two groups or 

 new centres : this is the diaster, or double star. 

 (e) The two groups of threads become further apart, 

 as if attracted by opposite poles ; but the two groups 

 remain still connected with one another by fine pale 

 threads. These latter differ from the others in not 

 staining with certain dyes, and representing the in- 



