I 



FILICINEM. 



435 



then cut off by a transverse septum and forms the single canal-cell of the neck, 

 which elongates with the growth of the neck and fills its cavity. According to 

 Strasburger a tendency to division, which however does not actually take place, is 

 indicated (Fig. 294, B) by the appearance in the neck-cell of several nuclei, a view 

 which is opposed by Janczewski. According to the latter observer the large central- 

 cell divides into an upper small cell, the ventral canal-cell (Fig. 295, ^, j), and into a 

 lower much larger cell, the oosphere, which subsequently rounds itself off. The 

 walls of the canal- cells swell up, become mucilaginous, and finally the watery muci- 

 lage together with the protoplasm of the canal-cells is forced out of the opened neck. 

 The antherozoids are retained by this mucilage and collect in large numbers before 

 the archegonium ; a number force themselves into the canal of the neck, often finally 

 stopping it up ; a few reach the oosphere, force themselves into and disappear in it. 



Fig. 295. — Archegonia oi Adianturn Capilltis-Vene.ris (X 800); A, B, C, E in longitudinal optical section ; D in transverse 

 optical section ; A, B, C before, E after fertilisation ; k neck of the archegonium, st mass of mucilage, e oosphere ; E, e the 

 two-celled embryo (observed after lying one day in glycerine). 



The entrance takes place at a lighter spot of the oosphere facing the neck, which is 

 termed the Receptive Spot^ (compare the oogonia of Algae). After fertilisation the 

 neck closes. 



The Asexual Generation (Sporophore) or Fern (as it is popularly termed) is 

 developed from the oospore or fertilised oosphere of the archegonium ^. At first the 

 surrounding tissue of the prothallium keeps pace with the increase of the embryo, so 



* Strasburger states that the act of fertilisation may be observed especially clearly in Cera- 

 topteris ; the forcible entrance of the antherozoids as far as the oosphere had previously been seen 

 by Hofmeister. 



^ [From the researches of Farlow (Quart. Jour. Micr. Sci. 1874) and of De Bary (Bot. Zeit. 1878) 

 the sporophore is frequently developed from the oophore in some Ferns {Pteris cretica, Aspidium 

 falcaium) without the intervention of sexual organs. The young Fern is produced as a bud from 

 certain cells of the prothallium. De Bary terms this mode of development Apogamy.] 



