234 Dr. L. Kny on the Structure and 



enclosed merely by a simple or double membrane, this, ae- 

 cording to Nageli, is always the consequence of the prepon- 

 derant increase of volume of the contents of the antheridium, 

 and of a compression of the enveloping cells thereby produced. 

 After the evacuation of the spiral filaments, these cells again 

 extend themselves. 



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

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

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

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

 bules or distinct nuclei furnished with nuclear corpuscles. As 

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

 the walls of the 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- 

 celled antheridium. The mother cells of the spiral filaments 

 are produced within this by free cell formation. Count 

 Leszczyc-Suminski, 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. 



AVigandf speaks very decidedly in favour of the unicellu- 

 larity of the antheridia 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 the 

 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. How 

 the mother cells of the spiral filaments originate, whether by 

 division or free cell formation, Wigand leaves undecided. 



Schacht J never found the antheridia unicellular in the spe- 

 cies investigated by liim [Pteris serrulata^ Asjjlenmm Petrarcce^ 

 Adiantum formosum^ and Asjn'dium violacevm) ; the nucleus 

 was ahvays enveloped by a single layer of limpid cells. 

 In his adhesion to Schleidcn'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, wdiich latter are also pro- 

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

 scription, Schacht himself expresses some doubt as to the 

 accuracy of his observations. 



* Zur Entwickelungsgescliiclite der Farrukriiutcr (1848), p. 10. 

 t Botan. Zeitung, 1849, p. 22. 



\ " Eeitrng zur EntTi-iclielungsgesclaiclite der FamikrJiutcr," Liunasn. 

 1849, Bd. xxii. p. 758 d soqq. 



