Devdopncnt of the Anther idium in Ferns. 241 



duced less numerously on tlic niaro-Inal cells. Their develop- 

 ment could be best traced on iilit'orm adventitious shoots, of 

 which each ramification, often, terminated with an anthcridiuni 

 (%. 13). 



The youngest rudiments observed by me were hemispherical. 

 The first septum that makes its ap})earancc in them has the 

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

 a narrow circle concentric with the peripheral boundary of the 

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

 circle) about 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, Avhich, 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. The other sister cell, which 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 Avith diluted solution of 

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

 acid, Ave observe a delicate divisional line, to Avhich a cell- 

 nucleus is applied both above and beloAv (fig. 13 h). This 

 septum, Avhich separates a sujierior shalloAV 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 Avith the further longitudinal groAvth of the 

 young antheridium, a stronger arching of this septum takes 

 place. After it has become about ])arallcl to the free outer 

 wall, an annular Avail, becoming slightly Avidened upAvards in 

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

 upper surface at an equal distance from the vertex all round 



(%. 1-1). 



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

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

 form of a truncated cone Avith its spherical basal surface turned 

 upAvards. With this the dcA^elopment of the antheridial enve- 

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

 ring cells, as Avell as the opercular cell, shoAV a nucleus, Avliich 

 is distinctly recognizable upon careful examination. Even 

 after the CA^acuation 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 



