286 THE GAMETOPHYTE, AND SEXUAL ORGANS [CH. 



approach the inner cell-wall. The mother-cell of the spermatozoids has 

 more dense granular cytoplasm. It divides at first regularly, by a vertical 

 wall followed by transverse walls, and again by walls at right angles to 

 these. Bi-partitions then follow in all the cells " until the number may be 

 a hundred or more, but the number is usually much less, about 32 being 

 the commonest" (Campbell, I.e. p. 316). They form a mass of polyhedral 

 sperm-cells, or spermatocytes, with dense granular cytoplasm, and large 

 nuclei. Thus the antheridia are not strictly standardised as regards number 

 of spermatocytes. Each nucleus is then transformed into the body of a 

 spermatozoid, of which, however, the forward end is partly of cytoplasmic 

 origin. The fully developed spermatozoid shows about three complete coils 

 in a tapering spiral (Fig. 20, p. 17). The very numerous cilia are attached at 

 a point a short distance back from the apex, and are found to arise from an 

 elongated "blepharoplast." As the spermatozoids develop the sperm-cells 

 separate, their walls appear thick and silvery, and give the staining reactions 

 of mucilage, but each inner wall remains intact so that on ejection each 

 spermatozoid is still enclosed in a delicate membrane, which swells in water, 

 and finally dissolves. A vesicle representing the remains of the cytoplasm 

 is conspicuous at first, but is soon lost from the escaping spermatozoid. 

 Prior to rupture of the antheridium the cells of the wall are compressed by 

 the crowded sperm-cells ; but after it is burst they become so distended that 

 they nearly fill the cavity. This behaviour, together with the swelling of the 

 mucilaginous walls of the sperm-cells, is the cause of the rupture of the 

 antheridial wall, which in this case is carried out " either by a central rupture 

 of the cover-cell or less commonly by a separation of this from the upper 

 ring-cell" (Campbell, Ic. p. 318). 



This description will apply generally for Leptosporangiate Ferns. There 

 may, however, be differences in the number and position of the segmentations 

 forming the wall, but the wall always remains a single layer of cells. The 

 number of subdivisions of the internal mother-cell, and consequently of the 

 spermatocytes, may also vary. It has been stated also that there may be 

 differences in the detail of dehiscence. But von Goebel holds that it is always 

 carried out in Leptosporangiate Ferns by extrusion of the distal cap-cell 

 or cells, in the way described by Schlumberger for the antheridia of Woodsia 

 ilvensis (Fig. 277). The mature antheridium {a) being tense by swelling of 

 the mucilage within, the cuticle bursts above the cap-cell {b). The latter 

 then separates as a whole, and is extruded, the adjoining cells of the wall 

 becoming distended inwards {b — d). The contents of the antheridium are 

 then thrust out by their pressure. Examination of an empty antheridium 

 from above often shows apparently an irregular hole {e), and it used to be 

 held that in certain Ferns the cap-cell itself ruptured. But in point of fact 

 it is extruded bodily, and the ragged appearance is due to the outlines of 



