282 



THE Gx'\METOPHYTE, AND SEXUAL ORGANS [CH. 



-§^a 



^' 



Fig. 272. TricJwmanes pyxidiferu7n. a — ^ == development of an an theridium ; (; = arche- 

 goniophore with five archegonia ; /, g= development of archegoniophore. ( x 1 50. ) 



as regards the manner of their origin a comparison with the flattened pro- 

 \.o\-\Q.vi\-&o{ Sphagnum. These epiphytic prothalli also produce spindle-shaped 

 gemmae, which are attached by one end to their 

 sterigmata. The groups of archegonia originate 

 from the marginal meristem, but are later sepa- 

 rated from it by regions which have passed over 

 into permanent tissue. (See von Goebel, Organo- 

 graphie, ii, p. 957, Fig. 951.) 



These somewhat similar forms of prothallus 

 are seen in Ferns not closely allied as regards 

 the characters of the sporophyte, and therefore 

 they cannot be held as phyletically of near 

 relation to one another. " Nevertheless they 

 may perhaps illustrate steps of progression 

 from a simple state, reminiscent of certain fila- 

 mentous Algae. It is easy to figure how from 

 the simple state shown by Schizaea a like state 

 with occasional flattened expansions, as seen in 

 Trichonianes, might lead to a generally flattened 

 form as seen in Hynienophylliun or Vittaria. 

 A strict localisation of apical growth at the distal end, instead of its being 

 spread generally along the margin as in Vittaria, would then give the 



Fig. 273. Hyutenophylluni dilata- 

 tum, Sw. Lobe of a prothallus 

 with a group of archegonia. 

 ^c>-=the individual archegonia; 

 Au = antheridia ; H = hairs. 

 (After von Goebel, from Engler 

 and Prantl.) 



