Development, and Structure of the Vegetable Cell. 27 
subsequently a green hue, a new vesicle in the mean time being 
developed in the centre of the cell. 
Kiitzing’s hypothesis receives support from, and was probably 
based upon those varieties in development in which the chloro- 
phyll-bands are in close apposition and not very oblique in di- 
rection, as seen in figs. 69 and 70, representing the Spirogyra 
orthospira, Nageli (?) (S. majuscula, Kiitzing ?). In these ex- 
amples the recognition of the limits of the several bands, and 
of the untenability of this view, is difficult, but it may be 
attained by the observation of the further development. 
On cutting through a joint-cell, as shown in figs. 70 and 72, 
and observing the contents as soon‘as possible after the water 
first begins to act upon them, we see, according to the phase of 
development of the joint-cell, the extrusion from the interior of 
a number of larger or smaller hyaline cells; the chlorophyll- 
bands usually break up into several elongated or spherical cells, 
which swell up more or less rapidly, display one or several very 
thick-walled starch-vesicles imbedded in the green mucoid con- 
tents, and, on fully emerging from the joint-cell into the 
water, suffer collapse. On the contrary, the mucoid mass 
which invests the hyaline cells resists the solvent action of the 
water. 
Some of the colourless cells are usually very much larger 
than the rest, two or four such being, as a rule, present in each 
joint-cell, one or two lying on either side of the cell-nucleus. 
Betwixt these, surrounding the cell-nucleus, are placed the 
smaller and similar cells. These structures are, in rarer in- 
stances, found at the ends of the cells near the septum (fig. 72). 
In those species in which the nuclear cell multiplies simul- 
taneously with the formation of new joint-cells, as in Spirogyra 
nitida, S. orthospira, &e., only one of these non-nuclear endo- 
genous cells is enlarged on either side of the cell-nucleus ; 
whilst in those other species, where the nucleus is little deve- 
loped, two such endogenous cells are mostly to be seen on either 
side of it. 
In fig. 72, one of these large colourless cells has been de- 
stroyed in making the section through the uppermost joint-ceil 
in the vicinity of the septum ; but the second has been consider- 
ably extended, and the smaller hyaline cells, which originally 
occupied the centre of the joint-cell, have been displaced 
by it. 
The water also acts similarly, although more gradually, upon 
the cell next to that which has been cut through, no doubt by 
penetrating through the exposed septum (figs. 71 and 72). In 
the corresponding cell (fig. 72) one of the two large colourless 
cells has protruded itself at each side of the joint near the sep- 
