INTRODUCTORY ESSAY. xxiii 



1 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 some present 

 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 classificatory 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 arM-nomplex organization, t and because there are no known fossil 

 plants which we can certainly assume to belong to a non-existing class or even family, nor that are 

 ascertained to be intermediate in affinity between.recent classes or families. J 



The progress of investigation may ultimately reveal the true history of the unrecognized vege- 

 table remains with which our collections abound, and may discover to us amongst 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 not advance us one step 

 towards a satisfactory conception of the first origin of existing Natural Orders of plants. 



Taking the Conifers as an example, whatever rank is given to them by the systematist, 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 classificatory 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- r1 i3 the sequence of the three classes, Dicotyledons, Monocotyledons, and Acotyledons; 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 phsenogamic plants as indications of superior organization ; but very many 



* la 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 brief 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) very few perennials. It has also been 

 well shown by Bentham (in his paper on the British Flora, read (1858) before the Linnasan Society) that an appear- 

 ance of stability is given to many varieties of perennials, through their habitual increase by buds, offsets, etc., which 

 propagate the individual ; and in the case of Ruhi, which comparatively seldom propagate by seed, a large tract of 

 ground may be peopled by parts of a single individual. 



f I have elsewhere stated that I consider the evidence of Algce having existed at 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 little value in the present inquiry, for I incline to believe that the ascertained geological history of 

 plants embraces a mere fraction of then whole history. 



