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In these estimates it is specially significant that, as in other physical characters, the differences of sex appear more strongly in highly civilized nations.
Other surprising revelations were likewise obtained from the researches made by A. Weisbach, which, although they extended to only 429 brains of inhabitants of Austria, were exclusively restricted to persons of sound mind. 26 The total weight was always first ascertained, and then the several weights of the cerebrum, of the cerebellum, and the pons varolii. But the most instructive fact was that the brain attains its greatest weight between the 20th and 30th year of life, and then till the Both year undergoes a diminution which increases to 10 per cent. This diminution extends simultaneously to all parts of the brain with the exceptions of the pons varolii, which increases till the 50th year.
From this we see that brain weights are comparable only at the same time of life. These researches have also confirmed a previous conjecture, namely, that the specific gravity of brains is variable; for the more capacious crania of the Germans contained a smaller weight of brain than other and smaller skulls, namely
Thus the capacity of the skull is of more importance in ethnology than the weight of the brain. We will further add that the minimum weight (986.5 gr.) of German male skulls was found in a person of 65 years of age ; a minimum of 889'1, female skulls, in one of 83 years of age.
We owe another discovery to Calori of Bologna, who by numerous measurements had already performed valuable services in the cause of science. He gives the weight of the brain in
26 Die Gewichts verhältnisse der Gehirne österreichischer Völker. Archiv für Anthropologie, vol. i. p. 190.
Sexual Differences in Brain Weights.
Italians of both sexes, but separates the cases according to the form of the skull.
Here we not only again see that the female brain is the lighter, but it also appears to follow that in both sexes the brachycephali have heavier brains than the dolichocephali. The lightest brain in a brachycephalic man of 22 years weighed 1024 grams, in a dolichocephalic of 34 years of 1088 grams, while the minimum weights in broad and narrow-skulled women were respectively 909 and 918 grams. 27
III.—THE OSSEOUS FACIAL APPARATUS.
In the perpendicular section of a skull, even the unpractised eye at once recognizes the region of the brain-capsule and the facial apparatus. In man, the latter occupies a relatively much smaller space, for it is not half so long, nor half so high, and is invariably narrower than the other. In apes, on the contrary, even in the highest, the size of the facial bones preponderates, and the animal expression of the head is chiefly due to the protrusion of the jaws.' A slight tendency to this formation of face in human races is termed prognathism. Peter Camper was the first who attempted to measure these structural proportions by means of the so-called facial angle. He drew a line from the external auditory passage to the nasal partition, and intersected it by a line from the front of the closed teeth to the most prominent part of the fore
27 Journal of the Anthropological Institute, vol. i. p. 117. London, 1872.
1 Peter Camper über den natürlichen Unterschied der Gesichtszüge, vol. xv. pp. 17, 21, 22.
head. The magnitude of the angle he took as a standard of a noble expression of countenance. Virchow has justly objected that this angle must decrease in old people by the development of the frontal sinuses, as well as by the retreat of the dental apophysis. But it was yet more unfortunate that Camper should have selected the nasal partition and the auditory passages as points on which to lay a so-called horizontal plane of the skull. A plane of this description has been sought by craniologists almost as eagerly as the philosopher's stone by the alchemists. This plane was supposed to lie horizontally through the head when the latter is poised over its centre of gravity with the least assistance of the muscles. The direction of the zygomatic arch seemed to fall in this plane, and the position of the skull was arranged to correspond with it. But it was soon found that this plane takes quite a different course in skulls of different races; that the zygomatic arch cannot always be followed, and that the skull must be a little raised, sometimes in front, sometimes behind.3 In this system the investigator relied on his own artistic feeling, which may occasionally vary. As H. von Ihering has shown, it has happened that an anatomist who, venturing on this slippery path, had repeated his measurements on the same skulls, after an interval of three years, found differences which amounted to more than 50 per cent.4 Moreover, such angles can be determined only on outline drawings of skulls. Consequently, science has at last been enriched by the system of the so-called geometric, or, perhaps more correctly, orthographic projection of the skull. Lucae, its inventor, placed the skull in the requisite position upon a firm support. Upon the skull, and parallel to the support, rested a glass plate, on which a dioptric instrument with a cross thread was moved in such a manner, that its optic axis constantly touched the outlines of the skull. The intersection of the threads was followed on the glass plate by a pen which registered in ink the course pursued.5 In this way he obtained a picture of the skull
2 Schädelgrund, p. 119.
3 Lucae, Morphologie der Racenschädel (1861), § 1. p. 42, and (1864) § 2, p. 31.
• Archiv für Anthropologie, vol. v. p. 396. 1872. 5 Morphologie der Racenschädel, § 1. pp. 10, 11.
as it would be seen from an infinite distance, somewhat as is the case with the moon seen from the earth ; these drawings are not merely free from all the defects of perspective vision, but they admit of measurements by the compasses.
Even less unanimity has been observed in the angular measurements of the facial apparatus than in the estimates of the size of the brain-capsule. Each anatomist went his own new way regardless of his predecessors, and very often applied the same appellations to angles which some other had sought at a different point. The results of the various kinds of measurement do not therefore admit of mutual comparison, and the painful spectacle of this dark mass of contradictions has drawn upon craniology a contumely perhaps not entirely undeserved, for the inducement to make increasingly factitious systems of measurement was often not so much the endeavour to provide ethnology with useful numerical formulæ as to find in the skulls of various races a corroboration of morphological theories.
In this state of things anthropology can but follow Welcker, the anatomist who has measured the greatest number of skulls ; his system, although, as he himself admits, imperfect and susceptible of further improvement, is fortunately the most satisfactory. Welcker searches for no horizontal plane, but merely determines the position of certain points in the facial apparatus, and does this regardless of the frontal bones.
The animal expression of the human countenance is due to the protrusion of the jawbones, and the degree is best determined by angular measurements. Virchow, even before Welcker, pronounced that prognathism, or the snout-like form of the face, is dependent on the shape of the base of the skull, although he did not conceive such a dependence as is shown by Welcker's measurements. The size of the angle at the sella turcica may be determined by a triangle, of which one side (fig. 3) is equal to the distance from the root of the nose to the sella turcica, the second to the distance from the sella to the anterior margin of the occipital foramen ; the third (6 n) from the latter back to the root of the nose. This angle of the sella turcica exceeds a right angle even in man, but in animals it becomes considerably greater. In the child and the young ape its size, or the degree of
flexure of the basisphenoid plate differs but little, that is to say, it amounts to 141° in the first, and 155° in the second case; but with increasing age this flexure becomes more acute in the human being, reaching 134', while in the ape it becomes more obtuse (174°). In this divergent tendency of growth Welcker recognizes a profound difference between man and beast. Yet, since this angle of the sella is neither visible nor measurable in a complete skull, it possesses a merely theoretical value for our purpose, arising from the fact that another angle of the face is correlatively dependent upon it. This angle is situated at the root of the nose, and is measurable in all skulls by the aid of a triangle, of which the
Fig. 3.--Section of the human skull in the direction of the sagittal suture. n, root of nose ; e, sella turcica ; b, anterior margin of the occipital foramen ; x, point on the super-maxillary bone above the alveoli. sides correspond with the distances from the root of the nose to the anterior margin of the occipital foramen (b), from this to the insertion of the alveoli (x), and finally from this back to the root of the nose.
It is obviously the angle at the beginning of the alveoli which controls the expression of the face, and in proportion to its magnitude the countenance appears to us ennobled. Weisbach found this angle to average from 70° to 72° in Amboynese, Javans, Banjarese, Chinese, and Buginese, 73° in 50 German men, 75° in Northern Italians, 76° in 24 German women, 77° in 28
6 Bau und Wachsthums des Schädels, pp. 80, 81.