DIVISION OF THE VEGETABLE CELL. 33 



lias gone before has been progressive towards it. There is one 

 feature which can now be seen, namely, the fibrillar arrangement 

 of the clear element of the nucleus on either side of the chromatin 

 plate, and through the remaining stage until the final division of 

 the cell this appearance is presented in a most striking manner. 

 We now come to the actual division of the nucleus. The plate 

 which we have seen formed splits into two, not suddenly ; com- 

 mencing at the circumference, it gradually proceeds until we have 

 two plates instead of one, lying near to and facing each other. This 

 stage I have seen best in the spore mother-cells of Equisetum, and 

 it is shown in Fig. 12. In the Tulip, as soon as the division of the 

 plate has taken place, the filaments are again seen ranging them- 

 selves longitudinally and parallel, but now they are found to be in 

 two sets, Fig. 6, and they recede from each other, as in Fig. 7, till 

 they reach the extremity of the achromatin, when the ends of the 

 filaments farthest from the centre unite, and we have the dyaster 

 stage as shown in Fig. 8. During this time the striated appear- 

 ance of the colourless portion of the nucleus, the Achromatin, be- 

 comes more marked, and henceforth claims greater attention. It 

 is now seen as a continuous band uniting the two chromatin groups. 

 The chromatin filaments now close up, the achromatin appearing 

 to increase and become more defined. The two daughter nuclei 

 now approach each other somewhat, the achromatin, bulging out 

 between them, and at the same time a row of dot-like thickenings 

 appear midway between the chromatin masses as shown in Fig. 9. 

 These thickenings denote the position to be occupied by the divi- 

 sion plate of the cell. Still this closing up of the chromatin con- 

 tinues, the bulging out of the colourless element also increases, till 

 a condition shown in Fig. 10 is reached, this being taken just at the 

 time when the cellulose plate has been deposited midway between 

 the nuclei. These now recede from each other, take up a more or 

 less central position in the daughter cells, and go into the resting 

 condition. 



Such is the complicated but most interesting process of cell divi- 

 sion. How different it is from what used to be held ! Instead of a 

 simple structureless substance becoming constricted in the centre 

 and finally divided, we have here a structure and character the 

 meaning of which is as yet but little known, and the process of 

 division is as complex as could well be imagined. Starting 

 from the resting stage, it (the parent nucleus) passes through cer- 



Journ. Q. M. 0., Series II., No. 1, d 



