20 
THE NATURAL SCIENCE JOURNAL. 
escape, aod these being very small and 
light easily float away on the air for long- 
distances or until they arrive at a spot 
suitable for germination. The globes in 
which the spores are borne are called 
spore-cases or sporangia and the fruit- 
dots, of which they are part, are called 
sort (singular sorus ). The sori are usu¬ 
ally borne on the back or tip of a veinlet 
of the frond. 
There is very little difference in the 
construction of the sporangia of various 
species, but if the sori of most other 
ferns be examined they will be seen to 
differ from those of the polypody in one 
important particular — when young, the 
sporangia are covered with a special 
membrane called the indusium. This is 
of various shapes, in some species like a 
tiny green cup holding the spore-cases, 
in others round, star-shaped, uniform, 
curved, linear or heart-shaped. The 
shape of the indusium and the way in 
which it is attached to the frond are im¬ 
portant points in the classification of 
ferns. 
In some genera of ferns the sporangia 
are not borne in sori on the backs of the 
fronds but instead occur in a continuous 
band along the margin as in the great 
bracken family, or covered by a reflexed 
portion of the frond as in the maiden¬ 
hair. Some others produce their spores 
on the fronds or parts of fronds that are 
very different in appearance from the rest 
of the plant. Of these the sensitive 
ostrich and cinnamon ferns may be cited 
as examples. 
AYhen a fern-spore finds itself in a 
moist situation it begins to germinate 
and soon gives rise to a minute, heart- 
shaped leaf-like body called the protliaJ- 
liuni. It is fastened to the soil by 
slender rootlets and develops on its 
under surface, organs analogous to the 
stamens and pistils of higher plants. 
From the union of these the new fern 
plant finally comes. As soon as the new 
plant is well started the prothallium usu¬ 
ally shrivels up and dies. In some exotic 
genera, however, the prothallium is said 
to live on and become a part of the plant, 
being renewed each year. 
Those who wish to experiment with 
the young ferns will find the rearing of 
many kinds from the spores a not very 
difficult matter. The fresh spores may 
be sown on a block of peat, the base of 
which rests in a saucer of water. The 
peat will absorb the water in the right 
cpiantity to suit the sporelings which soon 
appear. A damp shady place is the best 
in which to grow them. When the young 
ferns have put up two or three fronds 
they may be pricked out into small flower 
pots filled with a mixture of sand, leaf- 
mould, peat and ordinary soil. Another 
good way of growing ferns from spores, 
is to nearly fill a shallow pan with gravel 
placing on top of this a layer of sandy 
loam. After all has been thoroughly 
soaked with water, the spores may be 
sown upon the surface. 
Contrary to the general opinion it is 
not necessary to be a skilled botanist to 
have an acquaintance with the ferns. 
With any good botany in hand the mere 
identification of them is a comparatively 
easy task. One is not perplexed in 
studying ferns by a multitude of species 
as he is with flowering plants. In North 
America east of the Mississippi river 
there is less than a hundred different 
species, and one who can find half of this 
number in his own locality may consider 
hiinself very fortunate. Some whole 
