Fig. 107.
Fig. 108.
These general forms are associated with certain special forms of the separate organs.
Thus, for example, in proopic faces the palate is narrow, long and high; in platyopic faces, on the contrary, it is broad, low and flat; and the teeth corresponding to them may present a widely different appearance (long, narrow teeth; broad teeth).
Low Types and Abnormal Forms.—Low types, as we have already noted, depend upon the development of the face in its least noble parts (those of mastication); prominence of the cheek-bones and maxillary angles, great development of the upper and lower jaw (prognathism). These conditions are frequently accompanied by a low, narrow, or receding forehead, indicating a scanty cerebral development. Lombroso found a great prevalence of similar forms among criminals; but recent studies have disclosed the fact that such forms of facial development are in some way related to the environment in which the individual has developed, so much so that, on the basis of these morphological characteristics, we might almost succeed in delineating the physiognomies distinguishing the different social castes. In fact, while the aristocratic face is ellipsoidal and proopic, that of the peasant is characterised by a pronounced wideness between the cheek-bones, and that of the city labourer by a peculiar development in the height of the mandible. Thus the peasant has a broad face, and the city workman a somewhat elongated face, with very pronounced maxillary angles.
A real and important abnormality which indicates a deviation from every type of race or caste is facial asymmetry or plagioprosopy, analogous to plagiocephaly, and frequently associated with it.
It is necessary, however, in the case of the face, to distinguish instances of functional asymmetry, due to unequal innervation of the muscles in the two sides of the face; either from some cerebral cause, or from some local cause affecting the facial nerves. In such cases, the trophic state of the muscles and their contractibility being unequal, there is a resultant asymmetry, especially evident in the play of facial expression.
This form of asymmetry must necessarily be limited to the soft tissues and be due to a pathological cause; consequently it should not be confounded with the asymmetry due to a different skeletal development of the two sides of the face, an abnormality analogous to plagiocephaly, which is met with among degenerates as a stigma of congenital malformation. We owe to Brugia a most admirable method for demonstrating the high degrees of facial asymmetry which sometimes reach such an extreme point as to give the two halves the appearance of having formed parts of two different faces. This is precisely what Brugia shows by the aid of photography, uniting each half with a reversed print of itself, making the two prints coincide along the median line. The result is that every asymmetric face gives two other faces formed respectively from one of the two inequal halves, and presenting profoundly different aspects.