PROCEEDINGS OF SOCIETIES. 
143 
in various localities. There are some characters, the uniformity of which, of 
primary importance in considering genera and species, are hut secondary in con¬ 
sidering variety—such as character of venation, division of frond, fertility ; these 
are variously modified, according to the type of variety or subvariety, and, of 
course, to a certain extent, modify it in return. More generally we find the variety 
barren than the subvariety, but this may arise from some mistake of manipu¬ 
lation in cultivation. Indeed, for my own part, I believe most varieties may be 
made to produce fertile fronds, at least in the two forms under consideration to¬ 
night. 
All the groups thus formed are capable of general definitions, though it must not 
be expected that this general definition will detail every minute feature of variety 
found in the many analogous forms necessarily included under it, any more than 
the definition of species describes every minute feature of the individual plants com¬ 
prised, these being of little importance, provided the general characters are adhered 
to. To each of these groups a name is proposed to be given, by which it may be 
known, so that, for most species, it will suffice to quote this name to show what the 
form of the variety is. When two or more distinct forms of the same variety occur 
under a species, it will be but necessary to mark them in some way, as with Greek 
letters, &c., after each, and describe the salient points of difference. Ex. gr ., under 
Ath Filix faemina, we find three forms of a variety which we will call ramosum; 
these could be thus described—Ath. Filix faemina, var. ramosum (three forms). 
A, rachis branched; pinnules decurrent; apices of segments curled. B, rachis 
split into numerous linear segments; pinnae contracted ; apices of pinnae split into 
linear segments, tasselled. G, rachis and pinnae multifidly crisped at apices, and 
tasselled. This is the only species in which the forms of this variety cannot be re¬ 
ferred to one description, and when the species of Athyrium are definitely arranged, 
possibly the forms will be found to belong to different species. ( Vide second part of 
paper.) To enter into all the subvarieties and varieties would detain you too long. I 
shall, therefore, content myself with one of each, taking those which are the commonest, 
and which, fortunately, also happen to be the most fully worked out. These are— 
var. ramosum and subvar. multifidum. These both consist in a repetition of the various 
parts of the normal frond—this is a true duplicature, not a mere modification of other 
organs such as we see in double flowers. Every part of the aerial organs is found 
doubled ; some more commonly than others. In simple fronds we find it in the 
stipe, the rachis, and the apex of the frond. In compound fronds, in addition, it is 
also found in the pinnae and the pinnules—in fact, it may be found in every axis of 
the plant, primary, secondary, tertiary, &c. It is also found in the sori, though 
more difficult to demonstrate, as in some forms of Phyllitis scolopendrium ; I met, 
myself, with a wild specimen of Trichomanes speciosum, which I now show ; when 
I got it almost all the thecae were in pairs. 
Perhaps it is wrong to call the organs doubled, as they are not strictly so all 
through, but arise single, and then split into two, obeying a law of nearly universal 
occurence in nature, in accordance with which we find that the aberrant forms of 
the higher groups copy closely the normal type of those below them; thus, the 
dichotomy, which obtains in these forms, is the normal state of some, at least, of 
the Lycopodiaceae— ex. gr ., Selago, and is also seen in the seed lobes of some 
exogens. 
Some have proposed to separate into different groups the forms placed at the 
head of these groups— i.e., where the division affects the stipe, but this appears con¬ 
trary to analogy. They ground their opinions chiefly on its rarity of occurrence 
among species, but even they allow that it is not a constant character; we will find 
it is rare, but not so rare as either the division of pinnule, or sori, or thecas; and 
if we do not make any distinction between the rachis and stipe—which division, 
after all, is an arbitrary one—we will find the form not so rare at all—in fact, the 
nearer we go to the apex of the primary axis, the commoner will we find this 
division; and it is what might be expected, the modifying causes not having an 
opportunity to develop their action till the frond is partially developed, for if it acted 
previously, we would have two fronds instead of one. If we examine a simple frond 
we will find this well shown, as the rarest specimens are those divided deeply, and 
the commonest those having merely the apex split, often multifidly so. The 
