244 



Fig. 160. 



Melobesia siibplana. A, marginal part of Irontl seen 

 from the face. B, vertical section of border of frond. 

 C, vertical section of sporangial conceptacle. ^1 and 

 B 350: 1. C 200: 1. 



Transversal pores do not occnr, but transverse fusions frequently take place, most 

 frequently in ttie basal layer, but also between cells at a higher level. Abundant 



starch-grains occur in the ordinary vegeta- 

 tive cells. 



The sporangial conceptacles are nu- 

 merous and densely crowded. They are 

 only slightly prominent, but where they are 

 very densely placed, the single conceptacles 

 are often not prominent at all, the surface 

 being even (fig. 160 C). It is therefore not 

 always possible to indicate the outer dia- 

 meter of the single conceptacles. The ostiole 

 is lined by elongated cells radiating towards 

 the centre of the canal. At last they assume 

 the character of rudimentary hairs directed 

 inwards. Tlie middle of the conceptacle is 

 occupied by a conical columella of sterile cells, while the sporangia are placed in the 

 outer part of the conceptacle. A little stalk-cell was frequently seen under each 

 sporangium. The sporangia are always two-celled. I have 

 seen numbers of them, some preserved in alcohol, and can 

 assert that they were really two-celled, also at maturity. 



I have seen only one or two male plants containing 

 some antheridial conceptacles. These are small, completely 

 immersed. The bottom of the conceptacle is covered by 

 a layer of small, somewhat rounded cells, from which are 

 given off numerous elongated slightly curved spermatia- 

 produciiig cells a little incrassated upwards. I have not 

 been able to follow the development of the spermatia, but 

 I do not doubt that the elongated cells in question are 

 the spermatangia, which produce long clavate, slightly cur- 

 ved spermatia (fig. 161). The spermatia are not formed at the end of long thin 



sterigmata. The ostiole of the conceptacle 

 was in some cases provided with a long 

 spout resembling that of M. Lejolisii (fig. 

 161), in other cases no such spout was 

 present. 



Very few conceptacles with carpo- 

 gonia were seen. They were small, not 

 prominent ; the ostiole seems to be provided 

 with a peristome similar to that of the 

 sporangial conceptacles. Fig. 162 B shows 

 fully developed carpogonia with long 



Fig. 161. 

 Melobesia subplanii. Vertical sec- 

 tion of antlieridial conceptacle, 

 at right presumed spermatia. 

 560: 1. 



A D 

 Fig. 162. 



Melobesia siibplana Vertical sections of carpogonial con- 

 ceptacles. A with young, B witli fully tleveloped carpo- 

 gonia. B, 485: 1. />■ 420: 1. 



