So8 



MOSSES AND FERNS 



CHAP. 



oped vascular bundle, which is continued hito the stem as a 

 leaf-trace, and joins the axial cylinder. 



The Sporangium (Bozver (13)) 



There has been much disagreement as to the morphological 

 nature of the sporangiophores of the Psilotaceae. The two 

 chief views are the following : ( i ) That the whole sporangio- 

 phore is a single foliar member; (2) that it is a reduced axis 



Fig. 294. — Tmesipteris tannensls. A, Radial section of the young sporangiophore, 

 X112; sy, the young synangium; B, similar section of an older sporangiophore, 

 X112. The archesporial cells are shaded. C, Fully-developed synangium, show- 

 ing its position between the two lobes of the sporophyll, X3; D. a longitudinal sec- 

 tion of the synangium, showing the two loculi (all the figures after Bower). 



bearing a terminal synangium and two leaves. The recent very 

 careful researches of Bower upon the origin of the sporangio- 

 phore and synangium confirm the former view. He describes 

 the development in Tmesipteris as follows : 'The apical cone 



