various means of their concealing or defending their honey from insects, and their seeds from birds. On the other hand, swiftness of wing has been acquired by hawks and swallows to pursue their prey; and a proboscis of admirable structure has been acquired by the bee, the moth, and the humming-bird, for the purpose of plundering the nectaries of flowers. All which seem to have been formed by the original living filament, excited into action by the necessities of the creatures which possess them, and on which their existence depends.'

It is a matter of great interest to note in the foregoing passage that Erasmus Darwin had got hold of one side of the principle which his grandson subsequently elaborated into his theory of 'Sexual Selection '—the principle, namely, that certain structural peculiarities can be acquired, and when acquired may be intensified in the process of inheritance, owing to the fact that only those males possessing the peculiarity have the opportunity of leaving descendants. Erasmus Darwin, however, ascribed to a 'final cause' what Charles Darwin would have regarded as a result. We also see in the above, that Erasmus Darwin clearly recognised the significance and importance of what are now called 'protective resemblances.'* On the other hand, he curiously inverts the case where he speaks of the contrivances by which plants protect or conceal their honey from insects; and no one has done more than his own

* In other passages he gives a much fuller account of protective resemblances among animals, and adduces many instances, as to which he says that though the 'final cause' is easily understood, 'the efficient cause would seem almost beyond conjecture.'

grandson to prove how numerous, varied, and complex are the contrivances by which many plants attract insects, for the purpose of having their seeds fertilised.

In another passage, Erasmus Darwin makes special note of the extraordinarily rapid multiplication of living beings, and he recognised that the great majority of the young of each species must of necessity perish before reaching maturity. In this, however, he saw nothing more than a provision of nature to prevent the species, as a species, from suffering extinction. He failed, therefore, just at the point where Charles Darwin succeeded; and he does not appear to have suspected that it is this fact which forms the startingpoint of the long series of causes concerned in the origination of new species. No traces, in fact, of the law of Natural Selection,' as subsequently set forth by Charles Darwin, can be detected in his utterances upon this subject.

With regard to the general conclusions at which Erasmus Darwin arrived, he concluded that 'all animals have a common origin, namely from a single living filament, and that the difference of their forms and qualities has arisen only from the different irritabilities and sensibilities, or voluntarities, or associabilities, of this original living filament.' Hence he thought it 'not impossible but the great variety of species of animals which now tenant the earth may have had their origin from the mixture of a few natural orders.' Indeed, he goes further than this would imply, since he says in a later passage: From thus meditating on the great similarity of the structure of the warm-blooded animals,

and at the same time of the great changes they undergo both before and after their nativity; and by considering in how minute a portion of time many of the changes of the animals above described have been produced; would it be too bold to imagine that all warm-blooded animals have arisen from one living filament, which THE GREAT FIRST CAUSE endued with animality, with the power of acquiring new parts, attended with new propensities directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down those improvements by generation to its posterity, world without end?'

It is clear, therefore, that Erasmus Darwin not only taught the doctrine of the origin of species by descent with modification, but he regarded the course of development as an ascending one. This is rendered quite certain by a still later passage, in which he expresses the opinion that, 'from the beginning of the existence of this terraqueous globe, the animals which inhabit it have constantly improved, and are still in a state of progressive improvement.' He adds, 'this idea of the gradual generation of all things seems to have been as familiar to the ancient philosophers as to the modern ones; and to have given rise to the beautiful hieroglyphic figure of the TwToy woy, or first great egg, produced by NIGHT—that is, whose origin is involved in obscurity, and animated by εgos, that is, by DIVINE LOVE; from whence proceeded all things which exist.'

Not only did Erasmus Darwin accept the principle of evolution as applied to living beings; but he quotes

with approval the idea which Hume had put forth, that the globe itself 'might have been gradually produced from very small beginnings, increasing by the activity of its inherent principles rather than by a sudden evolution of the whole by the Almighty fiat.' Nor did he regard this view as being in the smallest degree antagonistic to the Theistic conception of the universe; for he adds: 'What a magnificent idea of the infinite power of THE GREAT ARCHITECT! THE CAUSE OF CAUSES! PARENT OF PARENTS! ENS ENTIUM!'

THE TRANSMUTATION OF SPECIES.

LAMARCK.

Up to the middle of the present century, naturalists in general had regarded 'species,' both of animals and plants, as immutable entities, founded upon abstract conceptions in the mind of a Creative Being, and necessarily incapable of modification except within the narrowest limits. It was held that each species had been created with a determinate and invariable organisation, by which it was specially adapted to the particular region which it inhabited. On this view, the habits of the species were the necessary result of its organisation, and as the latter was believed not to vary, so it was assumed that the former were also invariable. We have seen that Edward Forbes held this opinion, and that it was to the same doctrine that Cuvier lent the support of his immense influence and his vast learning.

At the present day, it is questionable if there exist any naturalists who regard 'species' as being independent creations, in the sense in which Cuvier and Edward Forbes held that they were. The principle of evolution,