INTRODUCTION. 
/ 
&c., the reticulation of the indusium and epidermis is very different, and the 
former is not furnished with stomata. In many genera this organ may be sup- 
posed a part of the frond itself turned over upon the thecae, as in Adiantum and 
Pteris, but I believe the reticulation is very distinct.* 
[Spores. When fertile leaves bearing ripe sori are shaken over a sheet of 
white paper, a fine brown or yellowish dust falls; this is composed of particles so 
small, as to be invisible singly to the naked eye. These particles are the spores 
of the Ferns, which, when sown, grow up into new plants, like the seeds of the 
Flowering Plants. They retain the power of germinating for a long period, even 
when dried and preserved in herbaria. They differ importantly from true seeds 
in many respects, the chief of which is the absence of an embryo or rudimentary 
plant in their interior. In their structure they agree almost exactly with the 
pollen-grains of Flowering Plants. When examined with a microscope, they 
are seen to be roundish, angular, or oval bodies, sometimes with a smooth 
surface, hut very often presenting little tubercles, lines, or reticulated ridges upon 
the outside. Close investigation shows that the outer coat is lined by another, 
thinner and smoother one, the two together forming a kind of little bag or sac 
(called by botanists a cell), containing merely a thickish granular liquid. 
Germination of the Spores. When these spores are sown upon a moist 
surface, they, after a certain period, germinate. The first sign of this operation 
is a bursting of the outer coat, and the protrusion of the inner in the form of a 
little tubular pouch. The contents of this pouch soon acquire a green colour, the 
tube becomes divided by cross partitions as it elongates, and, finally, the end first 
protruded from the spore enlarges in size, by the formation of cells, until it 
appears as a little, leaf-lilce, green plate, somewhat of the form of the heart on 
playing-cards, only much broader in proportion to its length, and with a deeper 
notch. The end of the tube which at first lay within the spore gradually 
withers ; but the point of the heart-shaped plate, corresponding to this end, 
becomes thickened, and sends out a quantity of hair-like radical filaments. Leaf- 
like bodies such as are here described are commonly to be met with under Ferns 
which have borne fruit, in Ward’s cases, or in pots kept in a moist atmosphere. 
They look like patches of some small Liver-wort, and have a glistening surface 
like many of these. 
So far there is nothing very remarkable in the development of these plants 
from their spores ; but the succeeding phenomena are exceedingly curious, and 
of a kind only met with in the Ferns and the Allied families. The merit of the 
discovery of the analogies between the reproduction of the Ferns and that of 
Flowering Plants is undoubtedly due to the Count Suminski, in whose work upon 
this subject, published in 1848, f the pistillidia of the Ferns were first described, and 
the nature of the antlieridia, previously seen by Nageli, first correctly interpreted. 
The details of the structure and the course of development were not accurately 
* The indusium is certainly related to the epidermis, and no true organ. The difference 
of reticulation is nothing, hairs and scales deviate much from the forms of the surrounding 
cells of the epidermis.— A. II. 
t Entwicltelungsgeschichte der Farrenkr’auter ; Berlin, 1848. 
