FERNS. 



253 



The secondary divisions (or first divisions of the pinnse) are the 

 pinnules. The stem, as in the Polypody, and in fact in all our 

 Ferns which have a stem at all, ia a rootstock or rhizome. But 

 here we miss the fruit-dots or sori, so conspicuous in our first 

 example. In this case it will be found that 

 theTe is a conlinuotis line of sporangia around 

 the margin of every one of the pinnules of 

 the frond, and that the edge of the pmnule 

 is reflexed so as to 

 cover the line of spore- 

 cases. Fig. 263 is a 

 very much magnified 

 view of one of the 

 lobes of a pinnule, 



Fig. 262. 



with the edge rolled back to show the sporangia. , Some of the 

 sporangia are removed to show a line which runs across the ends 

 of the forking veins. To this the sporangia are attached. The 

 v^ins, it will be seen, do not form a net- work, and SO are free, aa 



