326 M. Miller on the Development of Chara. 
Both however agree perfectly in being effected through cyto- 
blasts. But I consider it hardly necessary again to bring for- 
ward proofs of this kind of formation. They lie however, in the 
absence of anything like a secondary membrane, in each cell con- 
taining cytoblasts, and in the existence of real, although very mi- 
nute intercellular spaces ; hence the formation of new cells by 
the contraction of secondary membranes, or from the deposition 
of membranous matter upon projecting portions, as m Unger’s 
view, is here quite out of the question. 
We shall now consider the cortical layer. In the further pro- 
gress of the growth of the plant, the whorls of branches and of 
shoots become separated from one another (figs. 12, 13). Be- 
tween each whorl an internode is formed; and if we trace this 
process in its earliest condition, we find the cortical layer already 
prepared, running from internode to internode: hence it must 
happen that the number of utricular cortical cells is constantly 
double that of the number of branches; thus if there are six 
branches, there are twelve cortical cells, &c. We do not find 
any instances in which there is any great variation from the above 
laws. Thus, in each cell of the branches, which is immediately at- 
tached to the stem, two cytoblasts are usually transformed into two 
new cells; there is rarely only one present (fig. 17). Although 
this process is very difficult to trace, I have directly observed it. 
It is most easily followed by making extremely delicate longitu- 
dinal sections through the axis of the plant ; we then find the new 
cells with their cytoblasts, but always considerably turbid. Ina 
transverse section I have also found two cytoblasts in a cell, which 
were on the very point of expanding into cells. These new cells 
which are thus formed from cytoblasts now expand longitudinally, 
and thus run in a longitudinal direction between the epidermoidal 
membrane of the apex of the stem and the central utricle ; hence 
they do not run externally but internally, being inclosed by the 
membrane. In other respects their formation is similar to that 
of other cells, as already described in the germmating plant. 
Fig. 17. Pl. VI. represents a transverse section with the inter- 
node cut through beyond its margin. This section, and such may 
be frequently found, exhibits a central cell in its interior and seven 
placed around it. These are provided with separating walls, and 
divide the cavity of the stem into internodial cells. This is di- 
stinctly seen in a longitudinal section,as in fig. 19. P1. VIL, andina 
transverse section when made distinct by iodine, as in fig. 18, also 
in fig. 15. Thusit is at the same time clear that the formation of 
the cortical layer occurs upwards, and consequently resembles the 
growth of the apex. The entire process however proceeds si- 
multaneously with the development of the stem, the branches 
and the shoots. Its cytoblasts are formed at the same moment. 
