1904 } MERRIMAN;: VEGETATIVE CELL DIVISION 181 
cell to form the elongated cell of the procambium, so it may 
assume a square figure and produce the daughter cell of the 
dermatogen. 
In case of meristem cells destined to form the protecting cap, 
the chromatic substance gradually dwindles in amount without 
being accompanied by further increase of the cell body. The 
cytoplasm as well becomes reduced until finally both disappear. 
The process of division of meristematic cells without regard 
to the problems suggested by differentiation will now be treated 
in sections. 
THE ACHROMATIC FIGURE. 
The enlargement of the nucleus due to the growth of the 
chromatin in the prophase of division is accompanied by signifi- 
cant changes in the appearance of the cytoplasm. In figs. 2-5, 
8,9, which show stages in the formation of the spireme, the cyto- 
plasm appears to be uniform in structure. A comparison of the 
shapes of the nuclei indicates that the nuclei in the living cells 
must be amoeboid in these stages. As nearly as could be deter- 
mined, the changes in the structural appearance of the cytoplasm 
in the immediate vicinity of the nucleus just precede or accom- 
pany the transverse breaking of the spireme coil into chromo- 
somes. 
The first indications of the achromatic figure are to be seen 
in the aggregations of cytoplasm which appear first and remain 
the densest at the poles of the nucleus. The shape which these 
aggregations assume, and hence the final shape of the achro- 
matic figure, is dependent upon the shape and nature of the cell, 
as also possibly upon the fixative employed. The nucleus taken 
together with these cytoplasmic aggregations may be spherical, 
(jig. 24), or ovate (fig. 78), or elliptical (fig. 79). Occasionally 
these aggregations appear in such manner as to cause the chro- 
matic figure to be obliquely oriented, and hence to alter the 
division plane from the usual one at right angles to the long axis 
of the cell. 
Cells were seen in certain preparations, notably those fixed in 
chrom-acetic, in which the segments of a hyaline sphere seemed 
