Structure and Division of the VcgctaUe Cell. 209 



polar masses before them, thereby elongating the nuclear 

 barrel ; this is pretty well brought out in Plate X. figs. 7 

 and 8 ; but the repulsive influence now acts, not in a straight 

 line only. It radiates out all round, driving asunder the 

 fibres of the nuclear barrel, so that widening as well 

 as elongation occurs at the same time. In fig. 7 the 

 elongation is very pronounced, but the widening has just 

 begun; in figs. 8a and 86 the process is continuing, while 

 in fig. 9 it has reached its maximum. It should here be 

 noted that the nuclear barrel of figs. 8a and 9, while of an 

 average size, is not to be compared with figs. 86 and 10 ; but 

 these and some succeeding ones are on the whole exception- 

 ally large specimens. For the clear and telling preparation 

 from w^hich the drawing of fig. Sh was made, I am again 

 indebted to the ingenuity of Mr Jackson. The nucleoli at 

 length advance to the polar masses and bury themselves in 

 the nucleoplasm of these. A redistribution of nucleoplasm 

 now takes place ; from being heaped up or compacted on 

 the sides away from the centre of action, it now spreads 

 round and covers in the nucleoli. 



Though up to this point not the least trace of a cellulose 

 septum is visible, changes in the peripheral protoplasm have 

 not been wanting. The row of spots before mentioned, and 

 delineated in fig. 6, has increased to a double series, or 

 may form a strong band of irregularly disposed granules as 

 in Plate X. tig. 9. But after this three important and 

 simultaneous actions are induced, — (a) the polar masses, or, 

 as we may now term them, the daughter nuclei, have a new 

 membrane secreted round them ; {h) the cellulose septum 

 is faintly foreshadowed by a delicate ring of cellulose 

 deposited in the middle of the granules ; (c) the nuclear 

 fibres in the middle of the barrel are sundered, or separate, 

 and at a slightly later period develop a double row of small 

 discs — the cell-plate, between which still later the cellulose 

 septum will grow in. All these conditions are iairly illus- 

 trated in fig. 10, and we will now handle them in detail. 



(a) By botanists the nuclear membrane, even when 

 believed in, has been regarded, and perhaps naturally so, 

 as a pellicle that has formed on the exposed surface of the 

 nucleus. My preparations show that it is laid down inside 

 a quantity of protoplasm which envelopes it ; and we can 



TRANS. BOT. SOC. VOL. XIV. p 



