256 M. Miller on the Development of Chara. : 
brane*, a secondary, which is easily separated from the latter, 
and an internal more mucous one, in or upon which the true 
cellular contents (gonidia of Kiitzing) are situated. The latter is 
Mohl’s primordial utricle. .When treated with nitric acid the 
entire mass of the secondary membrane separates in an undula- 
tory form (PI. V. fig. 3). The contents of the cells, which con- 
sist of a greenish granular mass, in this stage of the spores are 
frequently absorbed at several places. The same occurs with the 
above five terminal cells, the surfaces of which press so closely 
together that there is no inlet into the spore (Pl. VII. fig. 35). 
The spore-sac is alone subjected to various alterations in form, 
the spore always remaining oval. 
The sporular membrane is likewise a closed covering of a round- 
ish-oval form, with a rounded summit and a truncated base 
(Pl. V. figs. 1. and 2), which flattens into a cell which will be 
subsequently considered. It is uniformly thickened, and thence 
cartilaginous, of a more or less brown colour, and has the same 
spiral windings as the spore-sac. They correspond to one an- 
other with tolerable accuracy, so that they are entirely or very 
nearly in the same plane. This spiral plane turns from left to 
right. The five extremities of these thickened, flattened cells of 
the sporular membrane unite at the apex as in the spore-sac, with- 
out forming any appendages. At the highest point the upper 
portion of the windings projects somewhat at an acute angle 
(Pl. V. fig. 6). 
The membrane of the nucleus lies close to the sporular mem- 
brane, but quite separate. It of course depends on the form of 
the sporular membrane, and differs from it merely in its more 
delicate, transparent, uniform texture, which is neither cellular 
nor spiral. 
The contents of the nucleus consist of starch-cells only ; these 
vary in size and are of a more or less rounded, somewhat com- 
pressed form. They are perfectly hollow, bursting either length- 
wise or in the centre (fig. 5) to discharge their fine granular 
contents, which also consist only of starch, as shown by the deep 
blue colour produced by iodine, and which is not unfrequently 
found between the parent-cells. By gentle pressure I was able 
to force these contents from the parent-cells, but I have not been 
able to observe this in loose pieces. 
As we have mentioned above, the spore is attached at its base 
to a four-sided, tolerably large cell (figs. 1 and 2). This contains 
a white, eranular; densely aggregated substance, and whilst within 
the spore-sac might be expected to perform some important part 
in its nourishment. Moreover in it the nutritious fluid which 
comes from the stem is rendered assimilable by the nucleus. 
* See § 6, where this is compared to the cuticle. 
