PE CULIARITIES. 
5 
cells. By the additional material thus obtained a little fern is soon 
formed, with a root stem and leaf of its own. The leaves are very 
small at first, but each succeeding one is larger, as the root increases, until 
the plant is fully grown. 
When the leaf is ready to produce fruit, in certain definite places 
(according to the kind of fern) there arise minute projections, half a 
dozen or more in a cluster, from the lower side of the leaf. These are 
composed of one cell each. As the cell grows, it divides, the one next 
the leaf becoming a kind of stalk, while the other divides into five, four 
of which enclose the fifth. Each of the four divides into an outer and 
an inner cell ; the outer ones form a stout ring, and the inner ones dis- 
appear, leaving the fifth cell floating free in the watery fluid which takes 
their place. This floating cell continues to grow till it breaks up into a 
number of bead-like bodies or cells which are the spores. The case con- 
taining the spores is called the spore-case. As this ripens, the ring of 
cells shrinks till it cannot endure the strain longer, when it splits cross- 
wise (in our ferns) and scatters the spores. These float out upon the air 
till they come to rest in some favored spot where they begin anew the 
great round of life. 
§ 5. Peculiarities. Explanations of Terms Used. — The leaves of 
ferns are coiled in a ball in the bud, unrolling as they grow, and growing 
only at the tip. This peculiarity has given them the name of “acrogens” 
(growing from the top). 
As the leaves of ferns are so peculiar, their parts have received 
special- names ; the so-called ‘^stem” is named the “stalk,” or “stipe,” 
and the leaf-like part the “ frond.” A frond is ^/z/fr^when it is not cut, 
toothed, nor divided in the least. It is toothed when the edge is notched 
like a saw (it is serrate when the teeth point toward the tip of the frond, 
toothed when the teeth point straight out, scalloped or crenate when the 
teeth are rounded). It is cut or incised when the edge is gashed deeply 
and irregularly. It is lobed when divided about half way to the midrib, 
(the midrib is the prolongation of the stalk, the term is also applied to 
the midveins of pinnae, pinnules and final divisions. ) It is parted or pin- 
natifid when divided almost to the midrib (leaving only a little of the 
green part of the frond between the parting and the midrib). It is 
divided when cut clean to the rachis (the midrib in all divided fronds is 
called the rachis). 
Divided fronds are said to be pinnate (because the divisions branch 
from the rachis like the veins on a feather; Latin pmna, a feather); 
the divisions are called pinna. If the pinnae are themselves divided, 
the frond is said to be bi-pinnate, or twice pinnate', and the divisions of 
the pinnae are called pinnules (little pinnae ). If the pinnules are divided, 
the frond is tri-pinnate , or thrice pinnate, and so on to quadri-pinnate, 
etc. Sometimes the frond is so much divided that the final divisions are 
only one forty-eighth of an inch long; the primary rachis, in that case, 
branches into secondary, tertiary, etc. rachises. 
By holding any delicate fern up to the light the midrib (of the 
main frond or its divisions) will be seen to branch. These branches are 
called veins; and their branches veinlets. The midrib, rachis, veins. 
