M. Miiller on the Development of Chara. 391 
completely inclose the central cell and prevent any access to it 
from without (figs. 30—35). As a proof I have given a figure 
(fig.36) from these young fruits, which may be compared with § 2. 
fig. 85. from them when ripe. In it the existence of the central 
cell is distinct enough at the intercellular spaces. The prepa- 
ration is placed upon its vertex, and thus the pressure of the five 
terminal cells against one another may be distinctly seen. 
This central cell forms the commencement of the nucleus, and 
the five external with the five* terminal cells form the young 
sporal sac. The sporal membrane is not yet developed. 
All parts of the fruit now become elongated, and as they in- 
erease, the cells of the sporal sac, which continue to become utri- 
cular, assume another position, 7. e. they turn spirally around the 
nucleus, whilst in their youngest state they had merely an up- 
right position. 
When the fruit has arrived at the limit of its longitudinal ex- 
tension it expands spherically, becoming at the same time filled 
with cells. These are again formed from cytoblasts, as may be 
seen in fig. 32, and it is probable that im the new cells thus 
formed new ones are again formed and so on, until the process 
of cell-formation ceases from the transformation of all the cells 
into starchy matter. This is a complete confirmation of Schlei- 
den’s observations on cell-formation in the embryo. I was not 
satisfied however by observing merely the true commencement 
of this formation (fig. 32); for the cells of the sporal sac be- 
come so speedily turbid, that the interior is rendered quite un- 
distinguishable, nor could I succeed in extending my observa- 
tions by dissections. 
When the fruit has attained its proper dimensions the remain- 
ing cells become thicker ; the primordial utricles, which- were at 
first scarcely perceptible, now become distinct, and the contents 
of the cells are formed. These are at first of a reddish colour ; 
they continue to become more intense, and subsequently become 
brownish yellow and green, which colour they retain. In the 
meantime the nucleal membrane has become thickened, and is 
now surrounded by another strong brownish membrane. This is 
the spore-membrane. It is merely the internal membrane of the 
spore-sac thickened, and may be subsequently completely sepa- 
rated from it. Thus are explained its perfectly homogeneous 
structure, flattened form, spiral windings and the interruption of 
this winding, the upper angles of which are always the most 
_* According to Meyen (Physiolog. vol. iii. p. 394) there are sometimes 
six sporal sac cells. 1 have never seen them myself. If however it be true, 
it is the same, as when we find the central utricle surrounded by six, seven, 
eight or more cells. Hence here the minimum is-six, in the former case 
five. 
