428 SIR RAY LANKESTER. 
peculiar green pigment occurs in Aphanizomenon flos- 
aque, with which I believe Clathrocystis to have a special 
relationship. This pigment is remarkable for changing, when 
dried with exposure to ght and air, from an apple-green 
to a blue verdigris-green tint. 
The jelly.—The cell-units of Botryococcus form a closely- 
set superficial layer one cell deep. ‘They secrete a jelly-like 
material which forms a denser capsule to each cell (Pl. 25, 
figs. 16 and 18), and is of a softer more watery consistence 
below that layer and between the adjacent capsules. Under 
slight pressure the capsules burst, and the cell itself is shot 
out of its position in the jelly into the surrounding water. 
The capsules burst by dehiscence of a concave-convex lid 
(fig. 18). . 
In the parts where one sub-spherical or kidney-shaped 
mass is adherent to similar neighbouring masses the jelly is 
often broken up into fibrillated strands (Pl. 25, fig.°5), the 
formation of which seems to be connected with the division 
of one original colony into separating sub-colonies. 
The colour of the jelly in all my specimens was either 
golden-yellow or a deeper brick-red. 1 gather from Prof. 
Chodat’s description that it may present itself as entirely 
colourless or with a greenish tint. 
I made no chemical tests of the nature of this jelly, but 
some are recorded by Chodat. 
The cell-units.—These as shown in the figures in Pl. 25 
are oblong and somewhat pyriform. They consist of a con- 
tinuous dense substance, which rarely exhibits vacuoles 
(fig. 17). From one to forty sharply marked granules are 
embedded in the dense substance and these granules are in 
some specimens green (fig. 3), in others they are yellow (figs. 
9, 10), in others brick-red (figs. 11, 12,13). 
The cells of Botryococcus when extruded from their cap- 
sules and the adjacent jelly exhibit no movement. They are 
devoid of flagellum or cilia. 
In the living cells it is not possible to observe any struc- 
ture in the cell representing a nucleus, but I found in 
