may still be distinguished. But the value of such remarks can be established only by the statistical average of a large number of observations, and these can only be obtained by long-continued accumulation. For the present the only result is that skulls with prematurely or abnormally closed sutures must be excluded from the measurements and not compared with the others. The sexual distinctions of crania are yet more perplexing. Welcker believed that in German skulls of which the sex was known, the female cranium was intermediate between the infantine and the male in all points susceptible of measurement. Our anatomists have therefore endeavoured to discover indications by which the sex of the skull may be determined. Craniological statistics have already shown that in highly civilized nations all secondary sexual distinctions are far more strongly developed than in those families of mankind which have remained in a state of barbarism. In the former the male brain-case is perceptibly more capacious than the female. On the other hand, it remains undecided whether the female cranium is narrower than the male. While Welcker found the cranium of women to be in nearly all races more dolichocephalous than those of men, Weisbach on the other hand obtained an average of 82.5 in Austrian women, and perceives a slight tendency to brachycephalism. On the other hand the inferior height of the cranium in the female sex has been pointed out by Alexander Ecker, who also attempts to recognize the female skull by the somewhat sudden transition from the flat crown to the vertical line of the forehead. Greater delicacy in the osseous prominences, diminished length of face combined with the greater size of the orbicular cavities, and inferior width of the lower jaw, are likewise supposed to distinguish the female cranium. Nevertheless, we are far from being able to determine with certainty the sex of an unknown skull. Several years ago, the English craniologist, Barnard Davis, wrote to A. Ecker that he had been compelled by the presence of the received sexual characters to pronounce a certain Bengalese skull to • Pruner Bey, Mémoire sur les Négres, pp. 328, 329. 1861 Sexual Differences. 51 be that of a man, and yet he knew positively that it belonged to a woman.9 The sex of skulls taken from old tombs cannot therefore be determined with certainty by their structure. Hence Virchow says, in his work on the ancient northern skulls at Copenhagen, "I do not in all cases feel competent to distinguish, definitely, between male and female crania, and I have therefore determined not to enter into an inquiry of this sort, that I may avoid arbitrary and doubtful divisions." 10 His and Rütimeyer in the same spirit observe, "We have not made a division of crania according to sex. Sexual distinctions based on mere appearance are too apt to lead to gratuitous assertions to be in any way trustworthy." Barnard Davis also states with respect to the catalogue of his craniological collection," "The sex was determined by the appearance, and follows no infallible rules; so that mistakes may easily have occurred." 12 Strict science, however, still demands a classification of skulls according to sex, in which the classes shall be no more comparable with one another than are two completely different species. Future collectors should therefore make every exertion to ascertain the sex of each skull at the site of its discovery. If ancient skulls, of which the sex is undecided, are thrown together, it may occur that two types or intermediate forms representing not two nationalities, but merely the sexes of a single nationality, may be based on the measurements. There is, moreover, a danger that if we accept the average of the sum of both sexes as types of the race, the average differences will be much smaller in amount than if men alone were compared with men. The proportions of the human skull have recently been determined even to the minutest details, so that the number of dimensions measured in a single skull has increased to 139.13 When we note this diligence and zeal, we may still hope that some acute observer may sooner or later succeed in detecting in some • Archiv für Anthropologie, vol. ii. p. 25. 1867. 10 Ibid. vol. iv. p. 61. 11 Crania Helvetica, p. 8. Basle, 1864. 12 Thesaurus Craniorum, p. 15. London, 1867. 13 See the three tables for twenty skulls of gipsies supplied by Isidor Kopernicki to the Archiv für Anthropologie, vol. v. p. 320. apparently unimportant proportional relations a key to the solution of this difficulty. Perhaps it may yet be discovered by what increase of the individual bones the form of the head is determined, 14 and for this reason the length of the individual sutures should be most carefully registered in all statistics. But the ethnology of our day must dispense with these preliminary labours to future knowledge, and must be content with the distinctions already established. Unfortunately, there is no universal system of measurement. In England and in France they set to work differently, while in Germany scarcely two craniologists follow the same method. "The object of the ordinary as well as of the scientific observer," says Virchow,15 "is to detect a definite connection between the shape of the cranium, the conformation of the face, and the structure of the brain." 16 Each will turn his attention to the measurement of those points in which he hopes to recognize this connection. But until such a connection is actually discovered we must content ourselves solely with measurements of the capacity. Retzius was the first who taught us to distinguish long and broad crania (dolichocephalic and brachycephalic) by comparison of diameters of length and breadth, although he did not distinguish accurately between the two forms. Even in obtaining the diameters of the skull, different methods are adopted, for the thickness of the cranial bones is very variable. If we apply a measure to the surface of a vertical section of a skull wall, we shall generally find the thickness of the bone plates to be from two to five millimetres. These variations do not affect the measurements as they would raise the longitudinal as much as the lateral diameters. But in other parts, and especially when we have to look for the longest axis of the skull, the frontal bone parts into a double (an external and an internal) osseous plate, and encloses cavities of considerable size. In the occiput, again, the internal and external layers are forced asunder by spongy capsules, and in the several cases the skull attains a thickness of 20 and 15 millimetres or more. Now, as these internal inflations of the bones 14 Virchow, Entwickelung des Schädelgrundes, p. 81. Berlin, 1857 Index of Breadth. 53 have assuredly no relation to the functions of the brain, and vary greatly in different members of the same family, and moreover increase with age, in determining the longitudinal diameter it does not seem right to place the points of the compass just over those bony enlargements. Barnard Davis therefore measures from the forehead (glabella) to the most prominent point of the occiput. Welcker, like him, places one point of the compasses on the forehead, but the other about an inch above the point of the occiput. Both thus avoid the places where the bones of the brain-case are most enlarged. After all, perhaps the most accurate plan, although at first sight it appears the roughest, would be to take the greatest axis in whatever place it may be found, for the development of the frontal sinuses, unimportant as it may otherwise be, certainly conduces to lengthen the cranium, while the amount of this elongation can be found with the aid of compasses. But as every system of measurement is justifiable, and none has hitherto acquired universal acceptance, we must for the present follow those craniologists who have furnished the greatest number of measurements susceptible of mutual comparison; these are Barnard Davis and Hermann Welcker. If we prefer the results gained by the latter, we do so with a reservation. The breadth of the skull is now measured at no fixed anatomical point, but search is made for the point at which the skull is broadest. Welcker, on the contrary, measures the breadth in a plane which, passing through the occipital foramen, divides the cranium into an anterior and a posterior half. Now, as all crania which are not perfectly oval, or, in other words, the great majority of crania, widen behind this plane of section, Welcker's measurements make all skulls appear on an average two per cent. more elongated than they seem to the eye. The longitudinal diameter is rated as 100, and the lateral diameter is expressed in a percentage of these units. This percentage itself is termed the index of breadth. Completely circular skulls, of which the index of breadth amounts to 100, and even more than 100, occur both in North America and among the Peruvians and the Chibcha of New Granada; they 17 Comp. Appendixes A and B. owe their form, however, to an artificial pressure of the skull, and must, therefore, be excluded from all comparisons. Otherwise complete roundness is most nearly attained by a skull from Tartary, of which 977 is the index of breadth; with this Huxley contrasts a head from New Zealand, though it is perhaps of Australian origin, of 629 as the narrowest of all known skulls. 18 Fig. 1.-Skull of an Inhabitant Fig 2.-Skull from New Zealand. of Tartary. Nevertheless, Barnard Davis possesses a so-called Celtic skull which, with a longitudinal axis of 82 inches, a width of only 4'9, has an index of only 58.19 The indexes of breadth, therefore, fluctuate between 58 and 98, if we take the most extreme cases into consideration. But the average is only between 67 and about 85. In this scale of nineteen notes all the average proportional breadths of human skulls are included. Welcker believes 20 that the index of breadth fluctuates from 74-78 in nations which in point of numbers include one-half of kind, and these he terms "orthocephali ;" they are better named man 18 Huxley, On two Extreme Forms of the Human Skull. Archiv für Anthropologie, vol. i. p. 346. 1866. 19 Thesaurus Craniorum, p. 63. 20 In his craniological communications to the Archiv für Anthropologie, vol. i. p. 346. |