508 



MOSSES AND FERNS 



CHAP. 



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

 leaf-trace, and joins the axial cylinder. 



The Sporangium (Bozver (^5)) 



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 



sy. 



FIG. 294. Tmesipteris tannensis. A, Radial section of the young sporangiophore, 

 Xii2; sy, the young synangium; B, similar section of an older sporangiophore, 

 Xii2. The archesporial cells are shaded. C, Fully-developed synangium, show- 

 ing its position between the two lobes of the sporophyll, X3J D, ^ 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 



