236 Dr. L. Kny on the Structure and 



into a tabular form, becomes converted by a series of bisections 

 into a globular group of cubical cells. 



Hentrey*, who does not appear to have been acquainted 

 Avith Thuret's work, not only gives a description of the struc- 

 ture of the antheridia agreeing with his throughout, but goes 

 a step further, and endeavours to ascertain the mode of pro- 

 duction of tJie annular cells. According to his observations, 

 there is formed in the mother cell of the antheridium, either 

 immediately or only after the separation of a basal cell has 

 taken place, an erect ring-like partition, which makes its 

 appearance simultaneously at all points. The rudimentary 

 antheridium now consists of an inner cylindrical cell and a 

 hollow cylindrical cell enclosing this. A horizontal septum 

 applies itself to the upper part of the ammlar partition ; and 

 by this the opercular cell, which is convex above, is separated 

 from the central cell. If the latter (or the products of its divi- 

 sion) be subsequently enclosed by two annular cells, these, 

 according to Henfrey, are always produced by the division of 

 the first formed annular cell by means of a septum running 

 round horizontally. 



It will appear from what follows that my observations do 

 not confirm the developmental history given by Henfrey. 



Wigand, in a second memoir f, in continuation of his pre- 

 vious communication, gives comparative observations upon 

 the structure of the antheridium in many species of ferns. 

 For a certain number of cases he maintains his previous opi- 

 nion of the unicellularity of the entire organ. In most spe- 

 cies he admits the existence of a proper antheridial wall, 

 which embraces the mother cells of the spcrmatozoids either 

 on all sides or only in part. The closed rings, tlie presence 

 of Avhich did not escape him, are described by him as " circles 

 of peripheral cells." The number of cells united to form a 

 circle is, according to him, usually four, sometimes five or six 

 [I. c. p. 46). 



Ilofmeister J afiirms, in opposition to Henfrey, that he 

 had repeatedly convinced himself of the correctness of Ins 

 previous statements upon the developmental history. Hollow 

 cylindrical cells are certainly recognizable in nearly mature 

 and in emptied antheridia ; but these, he says, are produced by 

 the lateral fusion of several cells by the absorption of their 

 transverse partitions. 



* " On the Development of Ferns from Iheh- Spores," Trans. Linn. Soc. 

 vol. xxi. p. 121. 



t " Weitere Beobaclituugen liber die Keiniungsgescliiclite tier Farrn," 

 Botan. Untersuch. 18o4, p. 44 et scqq. 



\ Beitriige zur Kenntniss der Gefasskryptogamen, ii. p. G04, note. 



