244 On the Structure of the Anther idium in Ferns. 



■\vherc tlicj suiTOiuicl the pair of closing cells of tlic stomata. 

 With regard to the mode of their formation, there is a still 

 unsettled difference of opinion between IlildeLrand* and 

 StrassLurgert ; hut both of them agree in thinking that the 

 ring cells are not formed as such, hut only acquire their pecu- 

 liar form subsequently. The antheridia of the Polypodiaceo3 

 and Schizreaccai consequently present the first example of a 

 direct inoduction of ring cells hy the formation of funnel-shajied 

 septa ; they show at the same time that this process, which 

 has hitherto been quite isolated in the vegetable kingdom, 

 admits of two modifications — the ring cells being in one case 

 cut off from a hemisjyhcrical , and in the other from a hell-shaped 

 mother cell. It is to be hoped that I may succeed, in other 

 species better suited for the investigation than those hitherto 

 examined by me, in tracing more accurately the process of 

 septum-formation and the behaviour of the cell-nucleus during 

 that process. Only then Avill it be possible to decide Avhether 

 this new form of cell-formation ranges itself immediately 

 beside that previously observed, or whether it is essentially 

 different therefrom. 



EXPLANATION OF PLATE VI. 



Fiy. 1. Younpcst observed developmental stage of a marfiinal antheridiiim 

 oi Atu'inua hirta. The central cell possesses the form of a bi- 

 convex lens. (Drawn after treatment with caustic potash and 

 muriatic acid.) 



Fig. 2. A someAvliat older state ; the bell-shaped cell is still undivided : 

 a, fresh ; h, after tlie same treatment as fig. 1. 



Fiy. 3. Half-grown antheridium ; the envelope is completely formed ; in 

 the central cell the first divisions are alread}- produced : a & b 

 as under fig. 2. 



Fiff. 4. A somewhat older state than fig. .3 : a & h as under fig. 2. 



Fiy. 5. Matin-e antlieridium. (It was evacuated during observation.) 



Fiy. 0. An antheridium just evacuated. (To the right the cell-nucleus 

 of the ring cell is distinctly recognizable.) 



Fiy. 7. An antheridium Avhich has long been evacuated, seen from above. 

 The inner folded wall of the ring cell is already strongly em- 

 browned ; the cell-nucleus is no longer recogiiizable. 



Fiy. 8. Half-developed antlieridium oi Ccratojdcris t]iaUdr(>idcf.^])\m^\n^ 

 obliquely from a marginal cell of the prothallium. The enve- 

 lope is completely formed ; the central cell is divided crosswise 

 into four cells. (Drawn aftei- treatment with caustic potash and 

 muriatic acid.) 



Fiy. 9. Two mature antheridia of the same species: a, with normal, uu- 

 symmetrical, 6, with abnormal, symmetrical basal cell. 



* " Ueber die Entwickelung der Farrnla-autspaltofTnungcn," Eot. Zeit. 

 1806, p. 245. 



t "Ein Beitrag zur EntwickeluDg.«geschichte der Spalttiilhungen," 

 Pringsheim's Jahrb. v. p. -300. 



