The chief features of the human nervous system having been thus demonstrated to us, we take our leave of the students and of the anatomical theatre, but before making our exit from the medical school we may turn aside for a minute to examine some specimens in its museum. In an out-of-the-way corner we come across the cast of a cleanly shaven head, mapped out into sixty little plots, according to the instructions of Dr. Gall, who founded the study of phrenology at the beginning of the nineteenth century. We notice that he has placed the organ of hope on that part of the head which lies over the convolution connected with the movements of the body ; the organ of amativeness is situated on the region of the cerebellum, while that of con-structiveness is placed over the inferior frontal convolution. We see that there is no correspondence between Gall's doctrine of phrenology and our modern knowledge of the brain. Yet to this extent Gall was right; the various parts of the brain have their own particular function. The day may come when by looking at the brain or even at the skull which encloses it, we shall be able to tell the capabilities of a child or man, but we have not yet reached that point. Even should that day come it is improbable that the phrenologist will be able to tell character as well as the ordinary man who merely observes the expression of the face, the tone of the words, the actions and the deeds of the person under observation. It is true that a wide and high forehead, indicating great development of the frontal lobes of the brain does incline us to anticipate capacity in a man, yet we are often mistaken ; we have known men of unquestioned ability with low and narrow foreheads. Even the size of the brain is not a safe indication. In most cases one can form a fairly accurate opinion of the size of the brain from the dimensions of the head. In the average man the skull and the soft parts covering it do not vary in thickness so much as to upset our calculations as to its size or volume. It is true that the chambers or ventricles within the brain may be dilated and thus give the brain a false size, but that is not a common condition. The size of the brain depends to a certain extent on the bulk of the body; tall men on the average have larger brains than small men, just as a Newfoundland dog has a bigger brain than a fox-terrier. The increase of brain which is directly due to increase in size of body gives no increase of brain power ; hence tall and bulky men are not necessarily more able than small and short men. Thus, although we cannot argue that because a man has a big brain he is a man of great capacity, yet the fact remains that many of the world's most famous men had large heads and big brains. In the average Englishman the brain weighs 1,860 grammes1 (forty-eight ounces); in Cromwell it is said to have been 2,231 grammes and in Byron 2,238 grammes. In Gambetta, the French statesman, it weighed only 1,294 grammes. Still, if size of brain is not a certain index of capacity, it must be taken into account; Broca found when he compared the brains of a group of eminent men with those of men of ordinary ability that the average eminent man had a brain eighty grammes above the ordinary. When the sexes are compared it 1 An ounce is equal to 28.3 grammes, is found that the brain in man is 130 grammes more than in woman on the average. Woman's smaller brain is due chiefly to her smaller body, for we have seen that size of body has a direct influence on the size of brain. Whatever view may be held as to the equality of the sexes, woman cannot be disqualified on account of the size of her brain. Therefore we must admit that size is not a valuable index of capacity, and the same must be admitted as regards shape. Certain American Indian tribes distort their heads and brains by the application of bandages in infancy and yet their mental capacity does not seem to be in any way affected. We see, too, that the human head varies much in shape; in some it is narrow and long ; in others broad and short; in others short and high or long and low. The long and narrow head is common in England ; the broad and short head in Germany and France, and yet, as far as we know, the brain which is within the short and wide skull has no advantage over the one within the narrow and long head. Thus all attempts to read character and mental capacity by examining the outward form of the head or of the brain have so far been in vain.
Before leaving the museum of the medical school there is another group of specimens we ought to examine, namely, those which show how the brain and spinal cord are formed during the early stages in the development of the human body. The early stages of the human embryo are represented by accurate models in which the various parts are greatly magnified. During the early part of the third week of development the brain and spinal cord are seen as part of the covering or epidermis on the upper surface of the embryo; the area of epidermis which forms the future nerve system is oblong in shape. In a model showing a slightly older stage the oblong area has become depressed to form a trough; presently the edges of the trough come together, the margins of the embryonic skin closing over the nerve trough, which now forms a tube enclosed in the back or dorsal side of the embryo. The front or head part of the tube forms the brain ; the hinder part forms the spinal cord. By the third month two outgrowths are evolved from the brain part of the tube ; one of these forms the cerebrum ; the other the cerebellum. To one who is unfamiliar with the facts of embryology it must seem a preposterous thing to suppose that our brains can have been evolved from a modification of an area of skin. Still these are the facts of development; how otherwise can they be explained except by supposing our brains are areas of the body-covering which have been modified ? Children are frequently born, as may be seen from specimens in medical museums, where the nerve plate has never been folded in but remains spread out on the surface and merging at its edges into the skin of the back and of the head. In such cases we see in the human body a hark-back to a condition that must have been represented in very low forms of animal life at an early stage of the world's history. That marvellous structure, the human brain, is the product of millions of years ; its history begins with life itself, millions upon millions of years ago.
When the reader leaves that strange place, a medical school, to which we have tried to introduce him, and emerges on the street to see men busy and energetic in all the affairs of life he will find it difficult to believe that there is aught in common between man's brain and that of any other animal created. As he walks along, however, he will notice how men differ; a man here and there has a brain weight of 2,000 grammes, and perhaps a corresponding ability; another has perhaps only 1000 grammes ; in seeking for man's allies it is not the highest but the lowest human types we must use as a starting-point. Amongst Australian aborigines it is not uncommon to find a woman with a brain weight of 1000 grammes or even less. When it is added that the gorilla, the chimpanzee, the orang, have brain weights that vary from 300 to 500 grammes he will conclude that there is a vast difference in even weight between man and the great anthropoids. There is a great gulf, but it is not a fixed one. A fossil form of man, Pithecanthropus it is named, had a brain which in point of size is intermediate between that of modern man and the gorilla's. There is an equally great gap between the great anthropoids—the gorilla, chimpanzee and orang —and the small anthropoids—the gibbons. If instead of comparing grown up men and anthropoids we compare them both at birth the difference is less. At birth the human brain weighs about 300 grammes, about one-fifth of the weight it ultimately reaches ; the brains of the anthropoids are only slightly less, 200 to 300 grammes. Thus, while man's brain is only about one-fifth of its adult weight at birth, that of the anthropoid is already two-thirds. Man has to be sheltered and educated; the anthropoid baby has to face the realities of life soon after birth. When we survey man and the anthropoids at birth, the brain difference does not seem an insuperable barrier between them. Indeed, in all mammals the brain grows much more rapidly than the rest of the body ; this is especially the case in man. By the end of the second year the human brain has reached two-thirds of its adult size, it has then reached the same relative degree of development that the anthropoid has reached at birth. There is another peculiar fact about the growth of the human brain; it has reached its maximum size by the twentieth year. After the twentieth year, or even a little before, it begins to lose in weight and goes on losing until old age, when the decrease becomes more rapid. As Professor Karl Pearson has said, man's prime is not a period, it is merely a point of time.