THE WILL IN NATURE.
nourishment, this last necessitating a variety of artificial means and a social and artificial system of rapine in general, the passing from hand to hand of stolen fruit, the placing of sentinels, &c. &c. Add to this, that it is especially in their youth, before they have attained their full muscular development, that this intelligence is most prominent. In the pongo or orang-outang for instance, the brain plays a far more important part and the understanding is much greater during its youth than at its maturity, when the muscular powers having attained full development, they take the place of the proportionately declining intellect. This holds good of all sorts of monkeys, so that here therefore the intellect acts for a time vicariously for the yet undeveloped muscular strength. We find this process discussed at length in the Résumé des Observations de Fr. Cuvier sur l'instinct et l'intelligence des animaux, par Flourens (1841), from which I have quoted the whole passage referring to this question in the second volume of my chief work, at the end of the thirty-first chapter, and this is my only reason for not repeating it here. On the whole, intelligence gradually increases from the rodents to the ruminants, from the ruminants to the pachyderms, and from these again to the beasts of prey and finally to the quadrumana [four–handed primates], and anatomy shows a gradual development
1 That the lowest place should be given to the rodents, seems however to proceed from a priori rather than from a posteriori considerations: that is to say, from the circumstance, that their brain has extremely faint or small convolutions; so that too much weight may have been given to this point. In sheep and calves the convolutions are numerous and deep, yet how is it with their intelligence? The mechanical instincts of the beaver are again greatly assisted by its understanding, and even rabbits show remarkable intelligence (see [Charles Georges] Leroy's beautiful work: Lettres Philosophiques sur l'Intelligence des Animaux, lettre 3, p. 49). Even rats give proof of quite uncommon intelligence, of which some remarkable instances may be found in the Quarterly Review, No. 201, Jan.-March, 1857, in a special article entitled "Rats."
COMPARATIVE
