Development of the AntJteridium in Ferns. 241 



duced less numerously on the luarLcInal eells. Tlieir develop- 

 ment could be l)C.st traced on tilitorui adventitious shoots, of 

 which each raniitication, often, terminated Avith an anthcridiuiu 

 (fig. 13). 



The youngest rudiments observed by me were hemispherical. 

 The first septum that makes its appearance in them has the 

 form of a funnel ; it attaches itself to the flat basal surface, in 

 a narrow circle concentric with the peripheral l)(jundary of the 

 latter, and widens upwards so as to strike (also in a closed 

 circle) .nbout the middle of the spherically arched outer wall 

 (figs. 11, 12). The lower (and at the same time the outer) of 

 the two sister cells, which, even at its formation, possesses the 

 form of a ring widened at the base and narrowed to an edge 

 above, retains this essentially ; it is afterwards incapable of 

 any further division. Tlic other sister cell, wliich is conically 

 narrowed at its lower end, distinctly exhibits a cell-nucleus in 

 this lower part. Its increase in length takes place exclusively 

 in its upper, free half. If a young antheridium in this stage 

 of development, when the upper part begins to distinguish 

 itself slightly, even in external contour, from the first annular 

 enveloping cell (fig. 13 a), be treated with diluted solution of 

 caustic potash, and, after being once Avashed, with muriatic 

 acid, we observe a delicate divisional line, to which a cell- 

 nucleus is a])plied both above and below (fig. 13 b). Tliis 

 septum, which separates a su]:)erior shallow bell-shaped cell 

 from the central cell (the primitive mother cell of the sperma- 

 tozoids), applies itself on all sides to the upper margin of the 

 first-produced funnel-shaped cell-wall, and is slightly curved 

 upwards in the form of a meniscus. 



Simultaneously with the further longitudinal growth of the 

 young antheridium, a stronger arching of this septum takes 

 place. After it has become about parallel to the free outer 

 wall, an annular Avail, becoming slightly Avideued upAvards in 

 a funnel-shape, attaches itself almost at right angles to the 

 upper surface at an equal distance from the vertex all round 

 (fig. 14). 



By this means the bell-shaped cell is divided into an inferior 

 ring cell and a superior opercular cell, the latter presenting the 

 form of a tnmcated cone Avith its sjjherical basal surface tunied 

 upwards. AVith this the development of the antheridial enAC- 

 lope, in the great majority of cases, is concluded. Both the 

 ring cells, as aa'cII as the opercular cell, shoAv a nucleus, Avhich 

 is distinctly recognizable upon careful examination. E\'en 

 after the evacuation of the antheridium, this is still retained 

 for some time in the ring cells (fig. 17). 



It is only after the foundation of the antheridial envelope 



