" NOVEMBER. 
323 
FERN CLASSIFICATION.—No. II. 
The spore-cases of Ferns, as already intimated, are made the basis of 
Fern classification. These spore-cases are minute hollow bodies, 
collected in groups of various forms, in different parts of the frond, and 
contain each a multitude of bodies, much more minute, fabulously 
invisible, which are the spores or germinating atoms. The latter, on 
account of their extreme minuteness, are seldom resorted to for primary 
distinctive characters, though they sometimes furnish useful auxiliary 
ones, both for the discrimination of genera and species. 
The spore-cases of all Ferns are one-celled bodies, that is to say, they 
have no internal division. They are, in the majority of cases, as seen 
under a microscope, made up of a thin layer of cellular matter, 
traversed by a line of short thicker parallel transverse cells, forming as it 
were a jointed belt, or ring as it is called, on the surface. This belt or 
ring takes a different direction in different groups, but occupies a similar 
position in Ferns of the same group ; hence, similarities in the position 
and nature of the ring are taken as the best technical characters for the 
purpose of grouping Ferns. The accompanying figures represent the 
principal differences which occur among these organs, and will be more 
intelligible than more lengthened descriptions. 
The presence of the ring (or annulus, as it is sometimes learnedly 
called), on the spore-case in some form or other, either nearly completely 
surrounding it, or in a more or less rudimentary condition, is the 
distinctive peculiarity of the great group of Polypodiacese, which com¬ 
prises by far the majority of the Ferns. Two small groups forming the 
remainder of what are recognised as Ferns, namely, the Marattiacese, 
and the Ophioglossacese, are distinguished by the absence of any such 
ring, rudimentary or otherwise, about the bodies which contain their 
spores. Thus we make the first step towards an intelligible classifica¬ 
tion :— 
Spore-cases having a jointed ring . . . Polypodiacese. 
Spore-cases without a jointed ring . . . { Ophioolossacm. 
These two obvious distinctions, to which, as they are connected with 
certain other differences which serve the same purpose, the initiated 
seldom have to resort, are the foundation of all satisfactory enquiries 
into the nomenclature of a Fern. 
The small groups, Marattiacese and Ophioglossacese are distinguished 
from each other by very obvious characters, less technical than the 
foregoing. The Marattiacese bear their sori, i.e., clusters of spore-cases, 
dorsally : in other words, on the back or under surface of their fronds, as 
is commonly the case among Ferns. The Ophioglossacese on the contrary, 
always have their spore-bearing or fertile fronds contracted or rachiform,* 
so that while the spore-cases are produced marginally, they seem to 
occupy the whole surface. It follows, that the coincidence of a ringless 
spore-case, borne marginally on a contracted frond, would lead certainly 
to the conclusion, that the plant in which such a structure occurred, was 
* Reduced to the appearance of the ribs or racliis. 
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