The volume, taken by itself, if it is not at one of the extreme limits, is not sufficient to justify a verdict of abnormality.
The terms macro- and microcephalic are, in any case, quite generic, and simply indicate a morphological anomaly, which may include many widely different cases, such, for example, as rickets, hydrocephaly, pachycephaly, etc., all of which have in common the morphological characteristic of macrocephaly.
In rickets, for instance, macrocephaly may occur in conjunction with a normal or even supernormal intelligence (Leopardi). Microcephaly, on the contrary, could never occur combined with normal intelligence, since it is a sign indicative of atrophy of the cerebro-spinal axis and diminution or, as Brugia phrases it, dehumanization of the individuality.
Normal Children
Abnormal "
Fig. 82.—Growth of Cranial Circumference.
In all the widely varied series of pathological and degenerate individuals who are included under the generic names of "deficients" and "criminals," there is a notable percentage of crania that are abnormal both in volume and in form; the percentage of crania with normal dimensions is less than that of the crania which exceed or fall below such dimensions, and among these there is a preponderance of submicrocephalic crania: a morphological characteristic associated with a partial arrest of cerebral development, due to internal causes and manifested from the earliest period of infant life.
The accompanying chart (Fig. 82) demonstrates precisely this fact. It represents the growth of the cranium in normal and in abnormal children. The abnormal are at one time superior and at another inferior to the normal children; but their general average shows a definite inferiority to the normal. Lombroso established the fact that among adult criminals there is an inferiority of cranial development, frequently accompanied by a stature that is normal, or even in excess of normality.
Quite recently, Binet has called attention to a form of submicrocephaly acquired through external causes, which is of great interest from the pedagogic point of view. Blind children and those who are deaf-mutes have, up to the seventh or eighth year, a cranium of normal dimensions, but by the fourteenth or fifteenth year the volume is notably below the normal, and this stigma of inferiority remains permanently in the adults. This fact, which is of very general occurrence, is attributed by Binet to a deficiency of sensations, and consequently a deficiency of certain specific cerebral exercises.