234 Dr. L. Kny on the Structure and 



enclosed merely by a simple or dout)lc membrane, this, ac- 

 cording to Xiigeli, is always tlie consequence of the prepon- 

 derant increase of volume of the contents of the antheridium, 

 and of a compression of the cnvelo])ing cells thereby produced. 

 After the evfttuation of the spiral filaments, these cells again 

 extend themselves. 



Count Leszczyc-Suminski * states that a free cell is pro- 

 duced in tlie interior of the mother cell of the antheridium as 

 this is arching itself up above its neighbours, and that the 

 contents af this, a homogeneous mucilage, show limpid glo- 

 bules or distinct nuclei fm-nished with nuclear corpuscles. As 

 soon as this cell lias advanced in its growth so far as to fill 

 the walls of tlie original projection, it shuts itself off from the 

 cells of the prothallium. Frequently a third, flattened cell is 

 formed between the two ; this serves as the bearer of the one- 

 ceUed antheridium. The mother cells of the spiral filaments 

 are produced within this by free cell formation. Count 

 Leszczyc-Suminskij indeed, also figures (Taf. 2. fig. 15) an 

 antheridium with a distinct cellular envelope ; but he describes 

 this, in the explanation of his figures, as a morbid state. 



Wigandf speaks very decidedly in favour of the unicellu- 

 larity of the autheridia of ferns, which he investigated in 

 several species, some of which, however, are not exactly de- 

 fined. According to him, they are frequently produced by tlie 

 direct metamorphosis of cells of the prothallium, without any 

 previous separation of an anterior elevated portion from the 

 great mass of the cells ; but usually the latter occurs. IIoav 

 the mother cells of the spiral filaments originate, whether by 

 division or free cell formation, AYigand leaves undecided. 



Schacht J never found the antheridia unicellular in the spe- 

 cies investigated by him [Fteris so-rulata, Asjjlenium PctrarccCj 

 Adiantum formosum, and Aspidiinn vioJaceum) ; the nucleus 

 was always enveloped by a single layer of limpid cells. 

 In his adhesion to Schleiden's opinion of the general occur- 

 rence of free cell formation, he supposes these cells of the wall 

 to be produced as vesicles in the interior of the mother cell. 

 One of them is assumed to become the primitive mother cell 

 of the cells of the spiral filaments, which latter are also pro- 

 duced by free cell formation. At the conclusion of his de- 

 scription, Schacht himself expresses some doubt as to the 

 accm'acy of his obseiwations. 



• Ziir Entwickclunpsprosclnclite der Farmkriiuter (1848), p. 10. 

 t ]k)ta?i. Zeitun-r, ]^<49, p. 2± 



\ •' Biitraj.-- zur J-^ntwickelungsgescliiclite der Faimkrauter/' Linnrea, 

 1840, 13d. xxii. p. 708 ct scqq. 



