"We shall finish our remarks on Sir Henry's work by making some observations upon a quotation made by Sir Henry Steuart from A Treatise on the Forming and Improving of Country Residences by the Author of the Encyclopaedia of Gardening etc.— an author who combines talent successful industry and enlightened benevolence in no common degree We are sorry to appear before this author whom we have long esteemed in opposition yet we regret the less as we consider him one of the few who prefer accuracy and truth to an old opinion and whose name stands too high to be affected by a casual misconception." (Matthew 1831, p. 295)As you can see, Matthew refers to the "Author of the Encyclopaedia of Gardening" rather than simply naming Loudon. This is quite strange, because Matthew was, otherwise, very outspoken and did not fear to openly criticise other scholars. In a previous post, I have already shown the further strange fact, that Matthew did not transport all the alterations that Steuart has taken the liberty to introduce into his quotation of Loudon. In some cases, Matthew reverted to the original usage of Loudon. This suggests that Matthew's re-quote was a dummy, and that Matthew did have Loudon's original at his disposal. He surely knew the Encyclopaedia of Gardening, for he chose to call Loudon "the Author" of that work rather than simply giving his name.
This strange evasiveness of the, otherwise, forthright Patrick Matthew suggests that he has lifted ideas from Loudon and did not want to credit that fact. By re-quoting Loudon via Steuart, he could pretend to not know the rest of Loudon's publications. Therefore, I searched the Encyclopaedia of Gardening for passages relevant to Matthew's ideas on natural selection.
The following passages show that everything in Matthew (1831), that is relevant to the idea of (macro-)evolution through natural selection, has already been present in Loudon's Encyclopaedia of Gardening. Here is Loudon's take on natural selection including, even, a notion of the transformation of species at the end (bold emphases mine):
" 843. Though plants are controlled by animals, yet they also control one another. From the various sources of vegetable reproduction, but particularly from the fertility and dispersion of the seed, the earth would soon be overrun with plants of the most prolific species, and converted again into a desert, if it were not that nature has set bounds to their propagation by subjecting them to the control of man, and to the depredations of the great mass of animals; as well as in confining the germination of their seeds to certain and peculiar habitations arising from soil, climate, altitude, and other circumstances. In order to form an idea of the manner in which these act upon vegetation; imagine that every year an enormous quantity of seeds, produced by the existing vegetables, are spread over the surface of the globe, by the winds and other causes already mentioned, all of these seeds which fall in places suitable for their vegetation, and are not destroyed by animals, germinate and produce plants; then among these plants, the strongest, and largest, and those to which the soil is best suited, developed themselves in number and magnitude so as to choke the others. Such is the general progress of nature, and among plants, as among animals, the strong flourish at the expense of the weak. These causes have operated for such a length of time, that the greater number of species are now fixed and considered as belonging to certain soils, situations, and climates, beyond which they seldom propagate themselves otherwise than by the hands of man." Loudon (1824. "An Encyclopaedia of Gardening." London: Longman, Hurst, Rees, Brown and Green, p. 186f)Here is Loudon's take on varieties within in species including, even, the analogy between artificial selection by humans and the unguided process of selection taking place, as it were, in nature:
" 1013. To form new varieties of vegetables, as well as of flowers and useful plants of every description, it is necessary to take advantage of their sexual differences, and to operate in a manner analogous to crossing the breed in animals. Hence the origin of new sorts of fruits. Even this practice is but an imitation of what takes place in nature by the agency of bees and other insects, and the wind; all the difference is, that man operates with a particular end in view, and selects individuals possessing the particular properties which he wishes to perpetuate or improve. New varieties, or rather subvarieties, are formed by altering the habits of plants; dwarfing through want of nourishment; variegating by arenarious soils; giving or rather continuing peculiar habits when formed by nature, as in propagating from monstrosities—fasciculi of shoots, weeping shoots, shoots with peculiar leaves, flowers, fruits, etc." Loudon (1824. An Encyclopaedia of Gardening. London: Longman et al., p. 216)
" 1016. The whole of gardening, as an art of culture, is but a varied development of the above fundamental practices, all founded in nature, and for the most part rationally and satisfactorily explained on chemical and physiological principles." Loudon (1824. An Encyclopaedia of Gardening. London: Longman et al., p. 216)Here's survival of the best adapted again:
" 6871. Sir W. Chambers and Price agree in recommending the imitation of natural forests in the arrangement of the species. In these nature disseminates her plants by scattering their seeds, and the offspring rise round the parent in masses or breadths, depending on a variety of circumstances, but chiefly on the facility which these seeds afford for being carried to a distance by the wind, the rain, and by birds or other animals. So disseminated they spring up, different sorts together, affected by various circumstances of soil and situation; and arrive at maturity, contending with other plants and trees, and with the browsing of animals. At last, that species which had enjoyed a maximum of natural advantages is found to prevail as far as this maximum extended, stretching along in masses and angular portions of surface, till circumstances changing in favor of some other species, that takes the prevalence in its turn. In this way it will generally be found, that the number of species, and the extent and style of the masses in which they prevail, bears a strict analogy to the changes of soil and surface; and this holds good, not only with respect to trees and shrubs, but to plants, grasses, and even the mossy tribe." Loudon (1824. An Encyclopaedia of Gardening. London: Longman et al., p. 957)We clearly have to count Loudon as yet another anticipator of the idea of natural selection, unless he just thought of his Encyclopaedia of Gardening as simply summarising the state knowledge in the art of gardening. In that case, Loudon's statement in his anonymous review of Matthew (1831) even gets another significance. In it Loudon wrote: "One of the subjects discussed in this appendix is the puzzling one, of the origin of species and varieties; and if the author has hereon originated no original views (and of this we are far from certain), he has certainly exhibited his own in an original manner." (Anonymous, attributed to Loudon, 1832. “Matthew, Patrick: On Naval Timber and Arboriculture.” Gardener's Magazine and Register of Rural & Domestic Improvements, vol. 8: pp.702-3). Matthew, like Darwin and Wallace, has simply put the pieces of the puzzle together, but discovered no new piece himself.
Loudon's Encyclopaedia of Gardening may even have been the common source of Matthew and Darwin. Darwin's notebooks titled 'Books to be read' and 'Books Read' (1838-1851) record for the 18 August 1842: "Skimmed through Encyclopaedia of Gardening ref: at end — [Loudon 1822]" (Darwin Online, http://darwin-online.org.uk/).
We can conclude that Matthew has lifted the ideas of competition and natural selection from other sources, Loudon in particular, and not thought them up himself. He did not cite his sources and, in this, his conduct met the same standards as that of other Victorian naturalists like Darwin.