He believes it to be shown by the existence of rudimentary or useless parts, such as the nipples of male animals, or the useless toes of swine, that animals have undergone changes—that monsters prove the same thing, but that in some cases monstrosities may be progressive rather than retrogressive, and aim at something to come. Species are nob permanent, but may be transmuted—the tendency being in increasing perfection. Animals are first aquatic, then amphibious, and finally aerial; and this is more or less seen in embryology. With respect to the Origin of Species in plants, he quotes Linnæus's opinion that at first there were only as many species as there are true natural orders. He discusses the theory of man's quadumanous descent.
He gives due influence to a Struggle for Existence as regards the extinction and modification or improvement of animals. With respect to Sexual Selection, he observes "the final cause of this contention amongst the males seems to be that the strongest and most active animal should propagate the species, which should hence become improved." He lays stress on the effect of the natural or artificial cultivation of animals, hence the changes brought about in the horse, dog, sheep, rabbit, and pigeon. He also attributes an influence towards the gradual production of species to the nisus to obtain food and ensure security. This last is rather Lamarckian than Darwinian, and it may perhaps be seen that even in respect to the effects of cultivation and sexual selection we have not lucidly expressed the salient point of the modern hypothesis—the certain but gradual effect in the production of species of slight, favourable variation, when developed by Natural Selection, rendered sufficiently efficient by length of time and unlimited numbers of the individuals. The elder philosopher does not tell us that the changes are so inevitable and undirected. He saw in the colouration of birds and their eggs, in the habits of insects, and in the modes of vegetable fertilisation, &c., as well as in physical nature in general, signs of design or extraneous intelligence. Nature, he says, is subject "to immutable laws impressed on matter by the Great Cause of Causes, Parent of Parents, Ens Entium." He is more generally correct in attributing some modification of species to climate and season, than to hybridity, which appears to have, on the whole, the reverse effect.
He seems to have taken an interest in the modes of fertilisation of flowers, but was thoroughly ignorant of the participation of insects in that act. The corella for him was » thing of beauty, and also for the respiration of the sexual organs; the nectar nourished the seeds, and was curiously guarded from the injurious depredation of insects, a superabundance of it only being, in a few instances, as in Cacalia suaveolens, acceded to them. He noticed the curios mechanism of the flowers of the broom, but did not discover that this mechanism is generally brought into play by the visits of bees. He gives curious examples of contrivances to effect ordinary fertilisation, mentions the ripening of different sets of anthers at different times, and the different length of sets of stamens in the same species, in Lythram and Lychnis for instance; as well as the great appetency of the stigma in some flowers, as Collinsonia, for foreign pollen, which he calls vegetable
