Ferns. 
3 
We now come to the characters by which Cryptogams are 
divided into groups ; and here some knowledge of plant physi- 
ology 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 sacks, 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, &c., 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 form a somewhat intermediate group between the two, but 
the method in which these are reproduced, distinguishes them 
easily from the higher vascular cryptogams. We find, then, that 
the Vascular Cryptogams, or as they are familiarly termed, the 
ferns and fern allies, are plants, which reproduce by spores ferti- 
lised, only after they leave the parent plant, and that they have 
stems and veins formed of vascular tissue. 
