INTRODTXTORY XXIU 
variety possesses of being fertilized by the pollen of its nearest counterpart, partly by the temporary 
stability of its surrounding physical conditions, and partly by the superabundance of seeds shed by 
each individual, those only vegetating which are well suited to existing conditions: an appearance of 
stability is also, in the case of many perennials, due to the fact that the individuals normally attain a 
great age,* and thus survive many generations of other species, of which generations 
characters foreign to their parents. 
36. In the above line of argument I have not alluded to the question of the origin of those 
families of plants which appear in the earliest geological formations, nor to that of vegetable life 
in the abstract, conceiving these to be subjects upon which, in the present state of science, botany 
throws no light whatever. Regarded from the elassificatory point of view, the geological history of 
plants is not altogether favourable to the theory of progressive development, both because the earliest 
ascertained types are of such high and complex organization,! and because there are no known fossil 
plants which we can certainly assume to belong to a non-existing cla^s or even family, nor that are 
ascertained to be intermediate in affinity between recent classes or families. X 
The progress of investigation may ultimately reveal the true history of the unre< 
table remains with which our collections abound, and m:,\ discover to us r-mougsi them new and 
unexpected organisms, suggesting or proving a progressive development; but in the meantime the 
fact remains that the prominent phenomena of vegetable palaeontology do nol advance us one step 
towards a satisfactory conception of the first origin of existing Natural Ord< rs 
Taking the Conifers as an example, whatever rank is given to them by the systematic, that they 
should have preceded Monocotyledons and many Dicotyledons in date of appearance on the globe, 
is a fact quite incompatible with progressive development in the scientific acceptation of the term, 
whilst to argue from their apparently early appearance that they are low in a elassificatory system is 
begging the question. 
Another fact to be borne in mind is, that we have no accurate idea of what systematic progres- 
sion is in botany. We know little of high and low in the Vegetable Kingdom further than is ex- 
pressed by the sequence of the three classes, Dicotyledons, Monocotyledons, and Acotylcdons ; and 
amongst Acotyledons, of Thallogens being lower than Acrogens, and of these that the Mosses, etc., are 
lower than Filices and their allies. It is true that we technically consider multiplication and com- 
plexity of floral whorls in phamogamic plants as indications of superior organization ; but very many 
* In considering the relative amount and rate at which different plants vary, it should be remembered that 
we habitually estimate them not only loosely but falsely. We assume annuals to be more variable than perennials, 
but we probably greatly overrate the amount to which they really are so, because a bra f personal experience enables 
us to study many generations of an annual under many combinations of physical conditions; whereas the same 
experience embraces but a fractional period of the duration of (comparatively) ror] few perennials. It has also been 
well shown by Bentham (in his paper on the British Flora, read (1858) before the Linmean Soei, ty) that an appear- 
ance of stability is given to many van a' their habknal increase by bnds, offsets, etc., which 
propagate the individual; and in the case of Eubi, which comparatively seldom propa-ate by - ed, a large tract of 
ground may be peopled by parts of a single individual. 
f I have elsewhere stated that 1 consider the evidence of Ahj-r having existed, a! a period preceding vascular 
Cryptogams to be of very little value. (Lond. Joum. Bot. viii. p. 254.) 
% It must not be supposed that in saying this I am even expressing a doubt as to there having been plants 
intermediate in affinity between existing Orders and Classes. Analogy with the animal kingdom suggests that some 
at any rate of the plants of the coal epoch do hold such a relationship ; but should they not do so, I consider this 
fact to be of Uttle value in the present inquiry, for I incline to believe that the ascertained geological history of 
plants embraces a mere fraction of their whole history. 
