30 HOFMEISTER, ON 



of the tangent, the antheridium assumes the form of a 

 mass of cellular tissue, supported upon a very short stalk, 

 consisting of four cells. Contemporaneously with the 

 first appearance of the young antheridium above the surface 

 of the joint of the stem, an annular wall of cellular tissue 

 is raised round the antheridium by means of repeated 

 division of the adjoining cells of the upper surface of the 

 frond (PL IV, fig. 29), which Avail, keeping pace in its 

 growth with that of the antheridium, surrounds it when 

 ripe, enclosing an open space above its apex. 



The cells, sixteen to twenty-five in number, of the outer 

 cellular layer of the ripening antheridium are flattened and 

 tabular (PL IV, fig. 30). Their walls are covered with 

 rather large chlorophyll-bodies (starch-grains surrounded 

 by a very thin green layer), which, when the organ is fully 

 ripe, assume a dull yellow colour. The inner cells continue 

 to divide for a long period by alternate longitudinal and 

 transverse septa ; so that the antheridium, when nearly ripe, 

 consists of a globular mass of very small, four-sided, tabular 

 cells, surrounded by a single layer of large, flat cells, con- 

 taining chlorophyll. Each of the small tessellated cells con- 

 tains a lenticular vesicle, in which a spiral thread is formed, 

 consisting of transparent mucilaginous matter (PL IV, figs. 

 30 32). When the antheridium is fully ripe, the cells of 

 the covering layer separate from one another at the apex ; 

 the small cells, whose primary intimate adhesion has been 

 destroyed by the softening and swelling up of the cell-mem- 

 branes, escape through the crevices, mixed with mucilaginous 

 granules, in the form of a thick pultaceous mass ; when 

 brought under water, they disperse themselves in the fluid. 

 The spiral thread enclosed within them (the spermatozoid) 

 soon exhibits an active whirling motion, in consequence of 

 which it resembles a closely wound watch-spring (PL IV, 

 fig. 32 *); it is still surrounded by the lenticular vesicle, 

 which, however, during the motion, can with difficulty be 

 seen. When the wall of the vesicle which envelopes the 

 spermatozoid bursts (which usually occurs after the vesicle 

 has been in the water for half an hour), the spermatozoid im- 

 mediately escapes through the fissure. It then forces its way 

 through the gelatinous, softened substance of the wall of the 



