The microscope and its revelations . spirally-coiled filament; and when theyhave been set-free by the bursting of the antheridium, theythemselves burst and give exit to their antherozoids (c),which execute rapid movements of rotation on their axes,partly dependent on the six long ciHa with which they are fur-nished.—The archegonia are fewer in number, and are foundupon a different part of the prothaUium. Each of them at itsorigin presents itself only as a slight elevation of the cellularlayer of the prothallium, within which is a large intercellularspace containing a peculiar cell (the germ-ce
The microscope and its revelations . spirally-coiled filament; and when theyhave been set-free by the bursting of the antheridium, theythemselves burst and give exit to their antherozoids (c),which execute rapid movements of rotation on their axes,partly dependent on the six long ciHa with which they are fur-nished.—The archegonia are fewer in number, and are foundupon a different part of the prothaUium. Each of them at itsorigin presents itself only as a slight elevation of the cellularlayer of the prothallium, within which is a large intercellularspace containing a peculiar cell (the germ-ceU), and openingexternally by an orifice at the summit of the projection; butwhen fuUy developed (Fig. 147), it is composed of from tento twelve cells built-up in iavers of four cells each, one uponDD 2 404 MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMIA. another, so as to form a kind of ckimney or shaft, havmg acentral passage that leads-down to the cavity at its base,wherein the germ-cell is contained. Into this cavity the Fig. X °//&553,|S^ Archegonium of Pteris serrulata :—a, as seen from above; a, a, a,cells surrounding the base of the oavity; b, c, d, successive layers ofcells, the highest enclosing a quadrangular orifice:—b, side-view,showing A, A, cavity containing the germ-cell; b, b, walls of the arche-gonium, made-up of the four layers of cells, b, c, d, e, and having anoperdng on the summit; c, c, antherozoids within the cavity; g,large extremity; h, thread-hke portion; i, small extremity in contactmth the germ-ceU, and dilated. antherozoids penetrate, so as to come into contact with the germ-cell; and, by the softening of the membrane at itsapex, they are even enabled to enter its cavity, within whicha minnte embryonic vesicle was previously embryonic vesicle, when fertilized by the antherozoidswhich move actively round it, becomes the primordial cellof a new plant, the development of which speedily com-mences.* By the usual process of
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