absurdities in the case of non-vital structures, it is plain that we are dealing with laws which we have but imperfectly comprehended, or with applications of them in which our perceptions are confused. Wherever we do understand vital mechanism, we see that its principles are identical with those which regulate the works of our own hands.

It is clear, then, that no slight modification of a normally efficient structure can greatly enhance its power, and least of all give to it an entirely new power. Nothing short of a new apparatus can do this. If we want our gun to fire north and east at the same moment, we must make and fit a new barrel to it; and if we wish it to fire in fifty directions at once, we must add forty-nine barrels to it: nothing else will do, turn and contrive as we may. No amount of exercise or favour of circumstances will enable it to take aim in two directions at once, nor cause it to develop other barrels from its side; yet naturalists have told us that the living gun can do this. But they have told us so, not by drawing upon their knowledge in a case really understood, but by taxing conjecture to furnish means of escape from a labyrinth of difficulties. The mɔment we analyze, and separate, and mentally dissect, we see that the living gun is as rigidly circumscribed by formative laws as the heaviest piece of ordnance ever turned out from a national dockyard; nay, circumscribed by the very same laws.

But the matter may be tested in a still more striking manner than this. We will take a gorilla on the one hand, and on the other a man of the same general size and weight. That man may belong to the very highest order of human intelligences: let us assume that he does so. In what does his superiority consist? In aggregate size and weight there is, by hypothesis, an equality in external conditions-in other words, in the primary motive power-there cannot be any difference worth mentioning. The gorilla is in a climate which perfectly suits him-in his native climate, the climate of his race from immemorial time. He has suitable food, that which he prefers, and which his race has always eaten; he has the best of society, according to his own notions and tastes-that of his brother and sister gorillas, and of his and their little ones; and, finally, he has all the required stimulus of antagonism, whether in the clashing of gorilla interests, or in the interference of more foreign foes. What greater external advantages can man enjoy? If food, climate, society, sympathy, and antagonism are more potent causes in his case, it can only be because the organism on which they act is of a superior kind.

Under these circumstances, then, whence comes the functional superiority of man? Size, weight of metal, and charge being equal, the gun can only be superior in function, in proportion as it is superior in structure.

There is no other element of power in the case. Let us look a little into details.

The bones which support, and the muscles which move these two beings must, in a general way, be equal in size and power; or where there is a structural advantage on either side, in any point, there will be found an equivalent functional difference. So with the nerves which excite these muscles, with the stomach which supplies the nourishment of the structure, with the blood-vessels which distribute this nourishment, with the lungs which perfect it, and with the glands which aid in the processes of formation, purification, or special secretion. In all these respects there is no material difference between the two animals, as far as the present question goes, or if there be, the balance is in favour of the gorilla. He will have more purely physical force, more brute power, than man: man will simply be superior in elegance of form, grace of movement, and refinement of taste.

Where, then, are we to look for that functional superiority which is acknowledged to be so vast? There is certainly no vast gulf in the portions which we have considered: if we are to find it anywhere, it must be in the portion not spoken of, the head. At the first aspect we see a very considerable difference between the two heads. That of man is very much more individualized. The forehead, the brows, the nose, the lips, the chin, the ear, and the cheeks have a separateness which strongly distinguishes them from the same parts in the simial head. Now this individualization, or, as it is also termed, specialization, is always, cæteris paribus, an infallible sign of organic complexity, and of elevation in rank; so much so that, in the absence of all knowledge of function, we should be justified in pronouncing man a vastly higher animal than the ape from this fact alone, trifling as it may seem to superficial observation. A similar individualization is presented in the hand and foot, organs so important in their relations to the mind. It is presented, in fact, in the entire body; and hence the grace and definiteness of the human form, so superior to that of even the handsomest of beasts, to say nothing of one of the very ugliest. In itself, this distinctness of marking would be a trifling matter; but when we regard it as a consequence and index of internal structural complexity it becomes of high importance, and this is what it actually is.

The head is an epitome of the entire body. It is divided into two portions: the face, which represents the trunk; and the brain, which represents the head itself. In a human structure of high order the head is always larger than the face; in the Simiade the proportions are always reversed; here again we see the indices of superior rank. But we must look closer than this.

The smallest normal human brain is stated to be twice the size of the largest

simial brain, while only one-half the size of the largest human brain. Thus the largest human brain is four times the size of the largest simial brain, as the smallest human brain is said to be four times the size of the smallest simial. Taking these proportions in the rough, as approximately true, and considering the subtle nature of nervous matter, they imply, to all appearance, a vast superiority in the human brain; and this superiority entails the following important dilemmas :-

In the first place, either the brain is a single organ, and therefore acts as a whole in every mental function, in every perception, desire, emotion, or volition; or it is an aggregate of two or more distinct but closely related organs, each having its own function. If one organ can perform two distinctly different functions, then the brain may be a single organ; but if no organ can do this, then the brain must be composed of as many organs as it has primarily distinct functions.

Then, as man

We will first assume that the brain is a single organ. has a brain four times as large as a gorilla, while, by hypothesis, his general size and weight are only equal to that of the gorilla, he ought to be able to throw four times the mental force into all his movements, intellectual, moral, and physical, that the gorilla can, unless his brain be of inferior quality and structure. Clearly he cannot throw four times the physical force into his movements. The gorilla, of the two, is the more powerful animal, and this power it cannot derive from the simple fact of having stronger bones or larger muscles. Apart from the muscles which move them, the bones are but dead weight; apart from the nerves, the muscles are mere flesh; while the voluntary nerves are as powerless as either until the brain flashes its lightnings into them. Unless, then, the brain have power, there is no voluntary power in the body at all, no matter what its size and proportions; and if, therefore, a simial brain can communicate as much momentum to a given mass and weight of living machinery as a human brain can, while yet it is only one-fourth the size of the human brain, it follows inevitably, on the hypothesis that the brain is a single organ, either that the simial brain is four times superior in quality or structure to the human brain, or that the human body is so relatively clumsy in its structure, and offers so many impediments to nervous transmission, that more than three-fourths of the cerebral energy are expended in simply overcoming its vis inertia, and getting it into motion. Now this dilemma is inevitable if the brain be a single organ. In this view it is the monkey who has the higher order of brain, not man. We must go to the gorilla, to the elephant, to the tiger, if we want to know what cerebral quality or structural mobility means-if we want to know what a nervous battery is.

But all this is ridiculous. The human body is not clumsy, the play of its muscles is not slow or ungainly, and the lightnings of mind flash not less vividly or potently in the case of man than they do in that of the gorilla, elephant, or tiger. And if not, then the brain is not a single organ.

Again if the brain be a single organ, it must enter into action as a whole in all its functions, and must be able to create the same amount of energy, and display the same intensity of results, in one direction as in another, whenever excited to a given degree; consequently the brain of the gorilla, which can produce a power equal to the human in the direction of anger, physical love, fear, combativeness, and various other volitions and emotions, ought to be equally powerful in every other mental direction; equally varied in its perceptions, equally tenacious in its memory, equally clear and powerful in its reasonings, equally lofty in its aspirations. But the very opposite of all this is the fact. In these directions the human brain is not simply superior to the simial, it is incommensurably superior-superior to the extent of a gulf, vast and impassable. Again, therefore, it is impossible, in the presence of these facts, that the brain should be a single organ. Were it so, it would be impossible for the animal mind to be a total blank, manifesting no power, capable of no excitement, in cases in which man is intensely excitable, while in others the two orders of mind are equally susceptible and equally powerful. The tigress is as violently excited by danger to her young as the fondest human mother; but yet, let her be satiated with food, and she will lie in her cage unmoved while a living chicken is deliberately pulled to pieces before her eyes, while the human mother will shriek with horror, and would probably swoon outright if it were a human being that was thus tortured. Now contrasts like these would be utter impossibilities were the brain a single organ.

What is true of animals as compared with men is equally true of men as compared with each other. Of two men, one shall have powerful passions, yet a feeble intellect; another shall be exactly the reverse. Of two equally intellectual men, one shall be a phenomenon in poetic fervour and imaginative power, and yet an arithmetical calculation of moderate dimensions shall be sufficient to fill his mind with mingled terror and amazement; while the other, who could sit down with delight to count the number of seconds in a geological epoch, may have a very profound conviction that all poetry and its belongings is mere rubbish and moonshine. Such contrasts would be impossible in the case of a single organ.

An organ, in the sense in which we are now speaking, is a mechanistic structure, exactly, and in all respects, fitted for producing a certain effect,

that effect being the necessary, in other words, the inevitable result of its normal action. Thus the necessary, the inevitable result of the normal action of the organ or organism of vision is the perception of light, that of the organism of hearing the perception of sound, and that of the organism of taste the perception of flavour. If these organisms could interchange functions, or if one of them could alternately perform all three functions, then a result would be necessary and not necessary, inevitable and not inevitable, at one and the same time, and in one and the same sense, which is a contradiction.

We never, therefore, find any simple or single organ performing two unlike functions. Whenever our anatomical knowledge is sufficiently accurate, we invariably see that complexity in the one case implies complexity in the other; and even had we no detailed knowledge at all in the matter, the law of causation is clear and absolute. Only like causes can produce like effects. Every variation in effect, therefore, implies a variation in the causation. If it be only the intensity of the phenomenon which varies, then it is the motive force which has been somehow modified: if the variation be one in kind, then the agent or structure has been modified or is different. But we cannot have the selfsame structure doing fifty different kinds of work, and working as a totality in every one of them. We cannot have like structures in two different animals, and yet have one of these structures doing fifty different kinds of work which the other cannot do at all, though both are equally normal in make and action, equally perfect in their kind, and both acting in all cases as totalities. We cannot have the same loom, fed in the same way, and yet working fifty different patterns. In a word, we cannot have the selfsame cause producing entirely different results; and if not, then the brain is a complex, not a single organ, and its parts can act individually as well as collectively; and two brains may differ greatly in complexity, while each is equally normal and equally efficient in its way. Let us now apply these conclusions to the case before us.

We have a man and an ape, by hypothesis, of the same aggregate size and weight; but the brain of the man is four times as large as the brain of the ape. As no one has asserted, and as we have no reason for supposing, that the intrinsic quality of the simial brain is superior to that of the human brain, whether in material or structure, while there are many and good reasons for supposing the contrary, we will give the ape the benefit of the doubt, and assume that the two brains are in this respect equal.

Under these circumstances, it necessarily follows that the larger brain must have at all points more intense functions and a greater amount of nervous power than the smaller, or that it must have parts which are