Chap, i.] CELLS. 9 



terstitial substance of the nuclear matter i.e., the pale 

 substance contained in the original reticulum of the 

 nucleus. Flemming calls this substance achromatin, 

 whereas the threads forming the original network, the 

 convolution, aster and diaster, he calls chroinatin, on 

 account of its readily staining with dyes. 



In this stage the whole figure resembles a spindle, 

 the nuclear spindle of Butschli (Fig. 5, F). 



(/) Further, all connection between the two sets 

 of threads is broken i.e., between the stars of the 

 diaster. (g) The threads of each set become greatly 

 convoluted. (A) A membrane appears for each set. 

 In this stage we speak of two new or daughter nuclei. 

 The cell protoplasm may commence to divide at any 

 stage between the one when the threads aggregate 

 round two centres, and the one when two distinct 

 daughter nuclei are present ; or the division of the 

 nucleus may not be followed by the division of the cell 

 protoplasm, in which case we have a two-nucleated 

 cell. In some instances, especially of invertebrates and 

 lower vertebrates, a peculiar sun-like arrangement of 

 fibrils of the cell protoplasm towards each of the two 

 stars of the above nuclear fibrils has been observed. 

 Martin has noticed, in pathological new growths, a 

 simultaneous division into three and four daughter 

 nuclei, after the mode of karyokinesis. Although 

 this indirect mode of division of the nucleus has been 

 observed in all kinds of cells in the embryo, and to a 

 limited degree also in the adult, it is not proved to 

 be the universal mode of nuclear division. On the 

 contrary, there is strong evidence that in amoeboid 

 corpuscles division of the nucleus follows the direct 

 mode, and it is also probable that other nuclei, under 

 certain conditions, may undergo the direct mode of 

 division. 



