182 PROCEEDINGS OP THE ANATOMICAL AND ANTHROPOLOGICAL 



tosis of the parietal bones at the sagittal suture. The premature 

 union of the parietal bones has prevented an increase in the width 

 of the skull in this region, whereas the persistence of the metopic 

 suture has allowed a compensatory increase to take place in the 

 width of the frontal region. Persistence of the metopic suture in 

 cases in which the sagittal or coronal suture is obliterated is not, 

 however, the general rule, and I am doubtful whether it is even more 

 common than in normal skulls of the same nationality ; thus, though 

 the persistence of the suture has allowed compensatory growth to 

 take place, it is not proven that the metopic suture has persisted as a 

 direct result of the increased intracranial pressure in this region. 



Nor do I think that the converse 

 condition, viz., diminution of intracranial 

 pressure, will act as a direct cause in pro- 

 ducing early union of the bones, though 

 it will undoubtedly favour their union. 

 The cranial sutures of microcephalic 

 idiots which have reached adult life are 

 usually open. It must be borne in mind, 

 however, that though the growth pressure 

 of the brain in these idiots must have 

 been less than in normal individuals, the 

 intracranial pressure of the cerebro-spinal 

 fluid, which is dependent on the blood 

 pressure, might be equal or nearly equal 

 to that of a healthy and normally developed person. 



It might, moreover, be supposed that early union of one-half of 

 the coronal, or lambdoid suture, might be due to defective develop- 

 ment of one-half of the cerebrum, and one case recorded by Virchow 

 might be regarded as favourable to this view. A woman who died at 

 the age of sixty-six had suffered from epilepsy from her earliest youth 

 and was hemiplrgir with atrophy of the whole of the right half of the 

 body. The skull was microcephalic and obliquely contracted. There 

 \va> synr.stosis of the upper part of the lambdoid suture, the hinder 



Fig. 1. 



