CHAPTER III. 
STRUCTURE. 
Haying ventured thus far into the Fern world, we must pause 
ere we further pursue our explorations, in order to inquire 
concerning the structure and constitution of its wonderful 
and beautiful inhabitants. Their position in relation to the 
rest of the vegetable kingdom we shall discuss anon. Here 
our inquiry must be limited to the field suggested by the 
heading of this chapter. 
Ferns, as we have seen, stand at the head of their lower 
world, and hence their structure more nearly approximates 
to the upper — and sunnier — world of flowering plants than 
any other members of their class. Like flowering plants, 
they have roots, stems, and leaves. Let us call the two 
latter by their proper names of caudices and frond*. The 
last-named designation is especially necessary as a means of 
distinguishing in Ferns those organs which, though in their 
appearance the most nearly like what we call leaves in 
ordinary plants, are nevertheless very different in some 
important particulars from leaves. The caudex, or stem, is 
the root-stock of a Fern. From it grow — downwards — the 
fibrous rootlets, and — upwards — the fronds. There are two 
principal kinds of caudex. The one is generally upright 
and trunk-shaped — sometimes, as notably in the case of tree 
Ferns, raised to some height above the ground ; the other is 
creeping in its habit, and is called a rliizoma. The rhizoma 
in some Ferns creeps along or with its circumference half 
