INTRODXJCTION TO CRTPTOGAMIC BOTANY. 



511 



oblique. The strongest arguments in favour of the notion are 

 derived from the production of bulbs or young plants upon the 

 fronds, especially as sometimes happens in place of sori. It is 

 true that the sporangium at first consists of a single cell, but 

 so does the leaf of a PhsEnogam, and the spores are formed by 

 cell-division, exactly like the pollen in an anther, which is 

 confessedly a metamorphosed leaf I do not, therefore, see 

 the same objection to the appHcation of the doctrine of me- 

 tamorphosis in this case as in Mosses, and more especially 



Fig. 113. 



a. Actiniopteris radiata. From a, specimen gathered at Beeder, by 

 Lieut. E. S. Berkeley. Natural size. 



h. Section of leaf showing indusium and insertion of sporangia. 



c. Sporangium. 



d. Pai-t of ring. 



e. Spores. The four last more or less magnified. 



