PLATE 1.

Brain in situ, Seen from Above after Removal of the

Calvarium.

After the calvarium has been removed the brain is seen covered by the dura mater (left half of the plate). The engorged veins (v) in the pia-arachnoid are seen through the aponeurotic, glistening membrane, which appears tightly stretched. On the surface of the dura, lodged in bony grooves of the vitreous table, are the branches of the middle meningeal artery, a. m. (ram. ant., r. a; ram. post., r. p). The superior longitudinal sinus (s. l. 8) is laid open.

On the right side the dura has been removed with scissors, and the convolutions on the convexity, covered by the pia-arachnoid, are exposed. The veins, which are always engorged (especially in the posterior portions), on account of the position of the body before the autopsy, empty into the longitudinal sinuses. On either side of the median line are the Pacchionian bodies (P), consisting of connective-tissue proliferations from the arachnoid, and covered with the arachnoidean endothelium; they are often abnormally developed, and produce marked depressions on the bones of the skull.

PLATE 2.

Right Hemisphere after Removal of the Meninges.

After the meninges have been removed with the forceps the convolutions (gyri) and fissures (sulci) of the hemispheres are exposed.

Frontal lobe: Superior, middle, and inferior convolutions; superior and inferior frontal fissures.

Central convolutions: Anterior and posterior central convolutions, divided by the principal fissure, or sulcus centralis of Rolando, which runs from above and behind, downward and forward. The junction of the frontal with the anterior central convolution is called the foot of the convolution (pfs, foot of the superior, pfm, foot of the middle, pfi, foot of the inferior frontal convolution).

Parietal lobe: Superior parietal lobule (subject to many variations), separated by the interparietal fissure (ip) from the inferior parietal lobule, the anterior segment of which is called the supramarginal gyrus, the posterior, the angular gyrus (pli courbé). The junction between the supramarginal gyrus and the posterior central convolution is similarly called the foot of the inferior parietal lobule. Occipital lobe: Superior and middle occipital convolu

tions.

Abbreviations.-P. F, frontal pole; P. O, occipital pole; pet, postcentral fissure; poc, parieto-occipital fissure; prei, inferior precentral fissure; pres, superior precentral fissure.