another peculiarity besides their vast relative size in all the more highly endowed animals, and especially in man. They are arranged in the form of irregular folds, which appear on the outer surface as sinuous convolutions. The nerve-pulp of which they are composed is a broad layer of considerable extent, but this is gathered and puckered up in order to enable it to be packed away in the cavity of the skull, somewhat as a handkerchief is when it is crushed up in the hand. These convoluted folds of the brain increase in their number and complexity, in every case, with the intelligence and mental capacity of the animal. They are not present in the brains of fish, reptiles, and the greater number of birds. In the parrot, a single slight furrow appears as a first indication of a folding of the substance. In bats, rabbits, hares, hedgehogs, and moles, the convolutions are not more marked than they are in the parrot. In the carnivorous and ruminating quadrupeds they are very abundantly developed, with the folds running only in a longitudinal direction. In the elephant and the apes, and in man, they are still more abundant, and are directed transversely across the breadth of the brain, as well as along, and in some places the furrows between them are so deep as to separate each hemispherical mass into subordinate protuberances, or lobes. In the apes and in man there are three of these at each side of the brain.

The convoluted arrangement of the hemispherical ganglia of the brain, in these highly endowed animals, is connected with another very remarkable peculiarity of structure, which goes far to explain the object for which it is designed. The brain is nourished by blood which is supplied from a vast vascular network, or coat of vessels, thrown over the outside of the mass, and this vascular net dips in between the contiguous surfaces wherever there are folds. Under this plan, the supply of blood is very much more abundant and free than it could possibly be if such extension of the vascular net into the interior of the brain-substance had not been carried out. The more convoluted the brain, the more copious is its nourishment by blood; and the more copious its nourishment, of course the higher is its activity, and the more energetic are its operations.

The brain-substance, which is folded into these convolutions in the higher animals, consists of an almost inconceivable number of very minute spherules of nerve-pulp connected together by a most intricate maze of nerve-threads, which traverse the substance in all directions, and which obviously serve the purpose of establishing a vital connexion between

*

the different groups of spherules.* The subtle operations, which are secondarily performed upon the primary impressions of sense, are accomplished by the instrumentality of this most complicated apparatus. The conscious impressions originated in the sense-ganglia are transmitted on to these penetralia of nervous life, and are there so dealt with as to be converted into ideas and memories, and to be made the material for the constructive operations of the mind. But the final and ultimate results of these mental operations, performed in connexion with the convoluted ganglia, appear to be returned to the proper organ of conscious sensation. The sensory ganglia are as much concerned with the conscious perception of ideas as they are with the simple impressions of sense, and the conscious life of the higher animals is made up of a combination of both sense-impressions from without, and of brain operations from within.

The psychological truth, which this comparative examination of the brain-structure of the different classes of animals teaches, is that there is some faculty, over and beyond that of mere sensational consciousness, wherever there are the hemispherical ganglia in the brain, superadded to the sensory masses, which are placed in the head directly behind the eyes, and which, in the vertebrated animals, are planted above the nose and between the ears, the three most specialised organs of sense; and that this superadded power is narrow or wide in proportion as the hemispherical ganglia are small and compact, or large and expanded into voluminous convoluted folds. Wherever there are convoluted hemispheres to the brain, there are certainly memory, the formation of ideas out of the impressions of sense, the association of sensations and ideas into connected trains, consciousness of ideas, capacity for the exercise of volitional impulse and intentional movement, the perception of the conditions of an external world, and the power of acting in relation to that external world according to the knowledge of it that has been imbibed. If such operations of the brain-hemispheres be accepted as indicating the existence of mind, then there is mind, to that extent, in the lower animals.

But the lesson has a deeper application than this. The hemispherical ganglia of the brain are enormously more complicated and relatively more vast in man than they are in any animals of lower grade. It is certain, therefore, that there is some brain capacity conferred by his organisation upon man

* See Edinburgh Review, No. cccv., p. 60.

which the lower animals do not possess. To determine what this superadded capacity is, that is peculiar to man and that is not shared with him by the lower animals, is the great problem which has to be dealt with by comparative psychology.

Dr. Carpenter, who has very exhaustively and carefully examined this question from the physiologist's point of view, and who stands prominent amongst the authorities who accept the existence of reasoning processes and emotional states, analogous to those which are exercised and experienced by man, in such sagacious animals as the horse, the elephant, and the dog, concludes that the distinction between the mental capacity of the lower animals and man consists in the circumstance that those animals are destitute of the power of reflecting upon their own mental states, and that they are therefore incapable of performing any mental process in which there is abstraction, or generalisation of ideas. The operations of mind, even in man, are in part spontaneous and automatic, and in part determined and directed by an effort of will. The superiority of man in mental capacity is due to the preponderance of the volitional faculties of the mind over its mere automatic activities, and to the discipline and growth which this favours and secures. In the lower animals, it is the spontaneous and automatic activities of the mind which are supreme. Here and there, as in the case of the elephant and the dog, there appear to be actions performed which indicate that these animals share to some limited extent in the higher mental powers that are preponderant in man. But, in most of these instances, a more rigid investigation of the facts makes it obvious that the results which have been observed are associated acts that can be primarily traced to the brains of men, rather than to any independent activity in the animals themselves. Wherever domesticated animals, which have been trained and educated by man, are concerned, a very large amount of caution is required to guard against the influence of this most fertile source of fallacy, as is abundantly proved by the eager and ready credence that is given in all directions to the current tales of the intellectual performance and rational conversation of birds as low in the scale of brain-organisation as parrots.

There is one peculiarity in the structural arrangements of the human brain which strongly favours this view of the question. As the hemispherical ganglia of the brain become more largely developed in the ascending scale of the animal organisation, white nerve-threads appear, connecting the several parts with each other, and assuming at last the form of fibrous

cords passing in various directions. These white cords are then termed the commissures of the brain. In the human brain such commissures are of exceedingly large dimensions. This is exactly what should be, if the distinctive character of the human mind, which is ministered to by the brain, is the faculty of constructing complicated and abstract ideas out of simpler perceptions and states. It is recognised by all physiologists that these commissural bands, so largely developed in the brain of man, are the material means by which the simpler conceptions of the mind are associated, sorted, and classed, and by which the more complicated perceptions are arrived at. The metaphysicians, who deduce all their conclusions from the observed operations of the mind, for the most part hold that the lower animals possess a kind of understanding built up directly from the impressions of sense, but that they have no capacity for abstracting ideas, and no originating or creative power; and that man has a higher and superadded attribute of mind, which can both abstract ideas and originate mental processes, and that these higher capabilities constitute the reason which is given to man and denied to the rest of the animal creation. But this reason of the metaphysician is just those higher capacities of abstraction, comparison, and judgment, which are physiologically provided for by the more ample convolutions and more abundant commissural connexions of the human brain; and the metaphysician therefore appears to have arrived at pretty much the same result as the physiologist, although he has travelled along an entirely different path. In all probability the lower animals can and do deal with their sensory impressions and with their sensational consciousness by that higher faculty which is termed the understanding by Kant, and which serves the purpose of so linking together these primary impressions of conscious sense as to convert them into intelligible thought, but are altogether destitute of the yet higher power, so energetic and supreme in man, which then deals with these products of the understanding, and, as a free and independent activity, reasons upon them, moulding them to a purpose, and voluntarily directing the associated currents in which they flow. It is of this higher and exclusively human power that Victor Cousin speaks, in his lectures on the philosophy of Kant, as the free and voluntary activity which assumes the government of the faculties, and which constitutes at once 'the personality and the consciousness.'* The mental opera

Kant held that human knowledge is derived from two quite distinct sources, intuitions immediately derived from the sensations, and

tions of the lower animals, in the absence of this directing activity, approach more to the character of waking dreams than of reasoning thought. They run along in their sense-suggested and unvarying trains without any higher control than that which is effected by the interpolation of fresh sensorial impressions; and they are only guided by man when he supplies these interpolated interruptions. They are more vivid and more coherent than human dreams only because, in consequence of their being waking dreams, they have mingled in with them so large a proportion of fresh sensual impressions. Concurrent sensations, intermixed with the memories and automatically driven notions, give a vividness and vigour to the images which the idea-woven dreams of sleeping men do not possess. But they are still essentially dreams, suggested by sense-impressions instead of by memories. This, no doubt, is a mode of considering the mental faculties of the lower animals which Dr. Lindsay would not accept. It nevertheless has, to say the least, quite as strong a claim to the acceptance of unbiassed enquirers as the alternative notion, so strongly advocated by him, that large bodies of men never attain to the mental and moral development of dogs.

Dr. Lindsay, in one passage of his book, urges that we know nothing yet of the final potentialities in mental capacity of the lower animals, and that we can hardly be said to do so until the same patient efforts that are lavished upon the negroes have been made by missionaries for the improvement of their anthropoid poor relations, and that, when this has been done, such results may be attained as will suffice to put an end once and for all to current sneers as to the psychological connexion between men and monkeys. If, however, this grand result of missionary enterprise were to be achieved, and to bring out the anticipated consequence, the disciples of Mr. Darwin would assuredly step in and say that the monkeys had been developed into men by the evolution, and therefore superaddition, of the rational faculties.

Notwithstanding the exaggerated strain which Dr. Lindsay throws upon the main line of his argument for the equality

notions which are formed by the understanding out of the intuitions derived from sense. The notions matured by the understanding are subsequently combined and organised into more complex and more abstract results by a third faculty defined as the reason. Victor Cousin adds to this third and highest faculty of the human mind an attribute of free and voluntary activity, which he thinks the conception of Kant did not include. It is almost certainly this power of free and voluntary activity of the mind which is deficient in the lower animals.