FERNS 
3 
This is what is known as circulate vernation , and is almost 
confined to ferns, though it also occurs among the Cycads or 
Kaffir Breads, and several other plants. 
We now come to the characters by which Cryptogams are 
divided into groups ; and here some knowledge of plant 
physiology is necessary. 
If the leaf of a moss be examined under a powerful 
microscope, it will be seen to be, not a solid mass as it 
appears to the unaided eye, but composed of numerous little 
sacs, or cells, containing liquid, and pressing one another 
into more or less regular geometric forms. The frond of a 
fern examined in the same way shows similar regular cells, 
seldom much longer than wide, and often roundish, square, 
or hexagonal. 
If, however, a longitudinal section from the stalk of a fern 
frond be examined, it will be found to consist of very much 
longer cells, cells so long, indeed, as to form continuous tubes 
up the stalk, for the free passage of the water, etc., sent up by 
the roots. These long cells are known as vessels , and plants 
formed of this tissue are known as vascular. Now, this is 
exactly the difference between cellular cryptogams and vascular 
cryptogams — the former including lichens, algae, and fungi, 
having cells only, while the vascular cryptogams, as well as 
almost all flowering plants, have vascular tissue throughout 
their stems and leaf veins, along with cellular tissue which is 
most developed in thin leafy parts. The mosses (Bryophyta) 
form a group somewhat intermediate between the two, but 
the method by which these are reproduced distinguishes them 
easily from the higher vascular cryptogams, which are spoken 
of as Pteridophyta. We find, then, that the Pteridophyta or, 
as they are familiarly termed, the ferns and fern allies, are 
plants, which reproduce by spores ; the sexual organs are 
borne on small and usually green structures ( prothalli ) which 
are formed as the result of germination of the spores, and the 
fertilized egg of the female organ ( archegonium ) grows into 
the fern plant, the stems and veins of which are formed of 
vascular tissue. 
i — 2 
