Page:Transactions of the Provincial Medical and Surgical Association, volume 1.djvu/87

 in the structure and gradual formation of the human body.

If we contemplate the interior of a skull, we shall at once perceive that the inner table has every where penetrated as far as it could into the recesses which open on the surface of the brain. Every convolution has hollowed out its corresponding mould in the vitreous table; every fissure between the convolutions has its corresponding ridge on the same table. The alæ minores, the angles of the petrous portions laterally, the crista galli and spinous process before, the vertical and transverse spines behind, all shew the tendency of this table to adapt itself to the fissures of the encephalon; nor does it ever neglect to do so, except where strong membranes projecting from it, nourished by its vessels, tense like bone, and sometimes becoming bone, supply its place; it is smooth and glassy, as all bones are which are subjected to a gentle but never-ceasing motion; and evinces, by this single property, its perpetual contact with the brain, and obedience to the impetus of its double pulsation. Lastly, the inner table has no relation, no attachment to any organ whatever, except the brain, its membranes, and vessels. To the protection of this viscus it is exclusively devoted, and a sagacious anatomist might infer as much from the ordinary course taken by the meningeal arteries.

The diploë may be considered merely as the cellular tissue connecting the tables of the cranium. It was in this state in the cartilage before it became bone, and preserves its connecting relations to each, unaltered, without performing any other immediate function. For the meditullium, which it secretes.