The structure of this genus well deserves examination.
Most authors agree in attributing to it a true peridium, whereas
L in k altogether denies its existence. It is true, that the
microscope shews the beautiful membrane which encloses the
sporidia, to possess a reticulated structure, dissimilar to that of
other plants equally low in the scale of vegetation, although
not unlike to the structure of more perfect cryptogamous plants.
He has therefore placed JFcidiwm among his E p i p h y t æ .
This arrangement at first sight appears unnatural ; nor can we,
after an attentive view, concur with him. W^hence does the
large and delicate (both in structure and colour) peridium of
Æ c id iw n Fini proceed ? It is of rapid growth, and, piercing
through a portion of the strong bark, forms a complete sac, enclosing
a multitude of sporidia, and apparently unconnected
with the neighbouring parts : even in those species which grow
on leaves, the epidermis of the leaf is ruptured, and a perfect
capsular body is disclosed, differing from it in colour, and substance,
and ifunction. W e cannot surely do wrong to follow
so close an analogy, in regarding this membrane as a true pe^
ridium, and in confessing our ignorance respecting the cause
and source of its remarkable structure.
Fig. I. Plants o f JE. Pint, nat. size, growing on the baric. Fig. 2. Ditto growing
on the teqf o f Pinus Sylvestris. Fig. 3. Magnified plants. Fig. 4. A
section. Fig. 5. Sporidia; and. Fig. 6. A portion o f the peridium, both
highly magnifed.