Last of all the various tribes of vegetables are to be enumerated amongst the inferior orders of animals.  Of these the anthers and stigmas have already been shewn to possess some organs of sense, to be nourished by honey, and to have the power of generation like insects, and have thence been announced amongst the animal kingdom in Sect.  XIII. and to these must be added the buds and bulbs which constitute the viviparous offspring of vegetation.  The former I suppose to be beholden to a single living filament for their seminal or amatorial procreation; and the latter to the same cause for their lateral or branching generation, which they possess in common with the polypus, taenia, and volvox; and the simplicity of which is an argument in favour of the similarity of its cause.

Linnaeus supposes, in the Introduction to his Natural Orders, that very few vegetables were at first created, and that their numbers were increased by their intermarriages, and adds, suadent haec Creatoris leges a simplicibus ad composita.  Many other changes seem to have arisen in them by their perpetual contest for light and air above ground, and for food or moisture beneath the soil.  As noted in Botanic Garden, Part II.  Note on Cuscuta.  Other changes of vegetables from climate, or other causes, are remarked in the Note on Curcuma in the same work.  From these one might be led to imagine, that each plant at first consisted of a single bulb or flower to each root, as the gentianella and daisy; and that in the contest for air and light new buds grew on the old decaying flower stem, shooting down their elongated roots to the ground, and that in process of ages tall trees were thus formed, and an individual bulb became a swarm of vegetables.  Other plants, which in this contest for light and air were too slender to rise by their own strength, learned by degrees to adhere to their neighbours, either by putting forth roots like the ivy, or by tendrils like the vine, or by spiral contortions like the honeysuckle; or by growing upon them like the misleto, and taking nourishment from their barks; or by only lodging or adhering on them, and deriving nourishment from the air, as tillandsia.

Shall we then say that the vegetable living filament was originally different from that of each tribe of animals above described?  And that the productive living filament of each of those tribes was different originally from the other?  Or, as the earth and ocean were probably peopled with vegetable productions long before the existence of animals; and many families of these animals long before other families of them, shall we conjecture that one and the same kind of living filaments is and has been the cause of all organic life?

This idea of the gradual formation and improvement of the animal world accords with the observations of some modern philosophers, who have supposed that the continent of America has been raised out of the ocean at a later period of time than the other three quarters of the globe, which they deduce from the greater comparative heights of its mountains, and the consequent greater coldness of its respective climates, and from the less size and strength of its animals, as the tygers and allegators compared with those of Asia or Africa.  And lastly, from the less progress in the improvements of the mind of its inhabitants in respect to voluntary exertions.