16 
GUIDE TO THE CORAL GALLERY. 
High Wall 
Case 
E. end of 
Gallery. 
the water (in a tumbler). On being magnified, the speck is seen to 
be a spherical sac uniformly dotted with green points and progressing 
by a peculiar revolving movement. Frequently the sphere con- 
tains several green “ daughter ” spheres, and these, again, “ grand- 
daughter ” spheres. The wall of the sphere is composed of a layer 
of cells (the separate green points), each provided with two flagella. 
The cells are embedded in a common jelly, each cell in a separate 
compartment, but connected with its neighbours by radiating strands. 
The outer surface of the sphere is covered with a pellicle through 
which the pairs of flagella penetrate, and the interior is filled with 
fluid in which daughter colonies may often be seen revolving. In 
addition to a nucleus and contractile vacuole, the body of each cell 
contains green chlorophyll granules. The daughter colonies inside 
the sphere escape in due time by rupture of the outer wall of the 
parent. Volvox is generally regarded by 
botanists as a plant. 
Goniumpectorale (Fig. 11b), a colonial 
organism belonging to the same family 
as Volvox , forms flat plate-like colonies 
composed of sixteen cells, each cell 
having a pair of flagella at its upper 
end. In one large section of Flagellata 
the cell is provided at its upper end 
with a collar, so the flagellum appears 
to arise from the floor of a basin. 
Codosiga cynisca (Plate IXa. in the Case) 
forms a branching colony. Some of the 
collared Flagellates secrete a horny cup or receptacle for the cell, 
as in the solitary Sailing coca napiformis (Plate IXa. in the Case), 
which forms a stalked horny cup containing the collared flagellate 
cell. Proterospongia haeckeli is a colonial form with Amoeba- like 
cells in addition to collared cells, all sunk in a common test. 
The ancestor of the Sponges, which are unique among the Metazoa 
in possessing collar-cells, was probably a collared Flagellate. The 
Mail Coated Flagellata have a flattened body, with a longitudinal 
groove from which a large flagellum projects, and usually, in addition, 
a transverse groove with a flagellum lying in it. These forms are 
mostly marine and often phosphorescent. Some species which have, 
a cuticular shell of cellulose, and which contain chlorophyll, are 
claimed by botanists as plants, but there are closely allied species 
without the cellulose investment or the chlorophyll. Ceratium tripos 
Fig. 12. 
Noctiluca miliaris, the Phos- 
phorescent Animalcule. Mag- 
nified 150 diameters. 
