4 
MORPHOLOGV OF THE CELL, 
an example, large cells, the oogonia (Fig. 2, /, Og), are formed in peculiar 
receptacles; the space enclosed' by the cell-wall is "densely filled with fine-grained 
protoplasm, which is at first homogeneous, but subsequently breaks up into eight 
portions (oospheres) ; these, completely filling up the cell-cavity of- the oogonium, 
press against one another and become polygonal. The wall of the oogonium 
consists of two layers ; the outer one splits, and the inner one protrudes in the 
form of a sac, which becomes distended by absorption of water ; in this enlarged sac 
the oospheres become globular 
(Fig. 2, //) ; when this bursts, 
the oospheres, now completely 
spherical, escape. By the fertilis- 
ing action of other smaller proto- 
plasm-masses, the antherozoids, 
these balls of protoplasm or oo- 
spheres are excited- to "further 
development; on the exterior of 
each fertilised oosphere or oospore 
a colourless substance makes its 
appearance, which hardens into 
a continuous cell-wall. The newly- 
formed cell now grows in two 
different directions in different 
modes, and produces, after further 
transformations (Fig. 2, V and 
IV), a young Fucus-plant. 
Sdll more clearly does the inde- 
pendence of the protoplasm of 
a cell show itself in the formation 
of the swarm-cells^ (zoogonidia) 
of Alg^ and of some Fungi. In 
many cases, as in Stigeoclonium 
insigne (Fig. 3, a), the proto- 
plasm of a cell filled with cell-sap 
cÖnlracts,.,ex'pels the cell-sap, and 
forms a roundish ball, which, 
escaping through- an opening in 
the cell-wall, swims about in the 
-water (C). While passing out, 
the protoplasm shows, by its motions and changes of form, that it is soft and 
extensible; but, once freed, it assumes a definite form. Usually after some hours, 
the swarm-ceir comes to, rest; iX:kiiled by proper means, Jhe. protoplasm contracts 
(E, F, p), and a delicate cell-wall may now be recognised, which it did not 
possess at the timie of its exit, when it began to fewim about. • When once at 
Fig. 3. — Sf2g-eoclo?n'u7n z/!si£-ne {after Näg-eli, Pflanzenphysiol. Untersuch- 
ungen, Heft \)\ A a. filament of the Alga consisting of one row of ce)ls, with a 
lateral branch; green protoplasm-masses (chlorophyll-bodies), imb'^ddecl ; in 
the colourless protoplasm of each cell not shown in the drawing; B the proto- 
plasm of the eel's contracting and protruding through openings in the cell- 
wall; C swarm-cells still without cell-wall; D one come to rest; at jg.and F 
killed ; the protoplasm / is contracted and shows the newly-formed cell-wall h ,- 
H a young plant grown from the swarni-cell ; G two cells of a filament in the 
act of dividing ; the protoplasm of each cell (x, y)_ has split into two equal 
parts, and contracted by addition of a reagent. ' •• 
^ [For the exact meaning of this term see Book II. Chap, i, the Introduction to Thallophytes. 
Thö'^t.erm. f swarming^. is. . applied *^to any apparently spontaneous motion .imparted to a naked 
protoplasmic body by vibratile cilia.] ' . . 
