SPORANGL^ 



241 



XXVIl] 



numerous sporangia originate in basipetal succession, overlapping one 

 another when mature like the shields in a Roman testudo (Fig. 511). The 

 orientation of the sporangia is always with the peripheral or distal face 

 outwards, and the central or basal face directed towards the receptacle. 

 The annulus is oblique and the dehiscence obliquely lateral. The sporangia 

 themselves are uniform in type for both genera: but they vary greatly m 

 size in different species. In the larger species they are almost spherical, as 

 in H. dilatatuvi: but in the smaller species they may be minute compressed 



Fig. 511. Trichomanes teneriim. Sorus in surface-vievy; 

 sporangia, issues from the two-lobed beaker-1 ' 

 sporangia. (Magnified.) (After von Goebel.) 



placenta, bearing radially distributed 



Fig. 513. Hymeuophylliim IVi'- 

 soiii Hk. Sorus in longitudinal 

 section, showing the receptacle 

 with divisions indicating inter- 

 calary growth, and the first 

 sporangia {s) orginating near to 

 the apex, (x loo.) 



Fig 512. Nos. 95, 96, 97, 98 = sporangia of /O""'^"^/'^.?'^'^"'"' 



dilatatmn Swartz, seen respectively from their two sides 



(95, 96), and from the central (97) and peripheral (98) faces. 



Nos. 99, 100, loi, 102 are similar figures, to the same scale, 



of Trichomanes radicans Swartz, 99 and 100 show lateral 



views, 101 shows the central, and 102 the peripheral faces. 



(Mix 50.) 



bodies, as in many species of Trichomanes (Fig. 512). The latter often show 

 a low spore-output, while in the former the numbers may be large. These 

 facts suggest that the family illu.strates reduction, though the type of sorus 

 and of sporangium is maintained. The development of the sorus shows that 

 the sporangia are borne in strictly basipetal succession upon the more or less 

 elongated receptacle. In a vertical section through a young sorus of 

 H. Wilsoni the young sporangia {s) are alread\- recognisable near its apex, 

 while below there are clear indications of active intercalary growth (Fig. 513). 

 The extent of this is usuall>- greater in Trichomanes than in Hymenophylhnn. 



16 



