. Public School Physiology and Temperance. top parts of the head—that is, thatportion in front ol the ears—are deep, high and broad, itis evidence of a large cerebrum, and generally indicativeof a high degree of brain power. The skull is not of the same thickness in allpersons. Over theeye-brows there is aspace between thetwo tables of extent and depthof this cavity cannotbe determined by out-ward observation. Aprominent foreheadis often due to alarge frontal space. The gray mattercovers the white por-tion, and is next tothe bone; but it isnot spread out onan even surface, nordoes it
. Public School Physiology and Temperance. top parts of the head—that is, thatportion in front ol the ears—are deep, high and broad, itis evidence of a large cerebrum, and generally indicativeof a high degree of brain power. The skull is not of the same thickness in allpersons. Over theeye-brows there is aspace between thetwo tables of extent and depthof this cavity cannotbe determined by out-ward observation. Aprominent foreheadis often due to alarge frontal space. The gray mattercovers the white por-tion, and is next tothe bone; but it isnot spread out onan even surface, nordoes it present onits outside a uniformsurface. There are a number of rounded edges, called con-volutions, separated by deep furrows. These furrows aremerely spaces formed by the convolutions dipping down andreturning back in a sort of a fold, just as a seamstress wouldmake a ruffle. These folds vary in depth in different partsof the brain and in different persons. The gray matter notonly covers the surface of the convolutions, but dips down. Fig. 34.—Upper surface of the Brain, showing theconvolutions and its double structure. THE NERVOUS SYSTEM. 109 into these diyiding lines, so that the two surfaces of thegray matter are in contact. The quantity of gray matter inthe brain is the true measure of brain power, Not onlydoes the depth of the folds vary in different brains, but alsothe thickness of the gray matter. To ascertain, therefore,the extent and amount of gray matter, it would be necessaryto open out the convoluted mass and measure its view of these facts, the value of phrenology, as practisedby bump-feelers, may be duly estimated. To define a per-sons character and mental ability by the outward appearanceof the skull is impossible. In order to arrive at a correctestimate, it would be necessary to know the thickness of theskull, the depth of the frontal space, ^he thickness of thegray matter, and the depth to which the layer dips downbetween the convolutions. 3.
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