may be left uncut, and hardened entire in formaldehyde for histological purposes.

Virchow's Method.-The brain is to be placed on its base in the same position as one's own. Press the hemispheres apart a little so as to expose the corpus callosum. Hold the left half of the cerebrum in the left hand with the fingers on the lateral aspect and the thumb in the longitudinal fissure. Then make an almost vertical incision with a long, slender knife through the roof of the left ventricle in its middle third, 2 to 3 mm. from the median raphé of the corpus callosum. The roof of the ventricle is to be slightly raised vertically by the thumb, so that the incision, which must not be too deep, may not injure the basal ganglia. The incision is to be continued into the anterior and posterior cornua. Then make a long incision from one end of the above cut to the other, passing just outside of the basal ganglia at an angle of about 45°. Repeat the process on the right side, turning the brain half around. Next seize what remains of the corpus callosum and fornix in the middle, lift them, and cut through from below up, passing the knife through the foramen of Munroe. The parts are then turned back, exposing the velum interpositum and the choroid plexuses. By drawing back the velum interpositum the third ventricle is uncovered.

The corpora quadrigemina are exposed by cutting transversely the right posterior pillar of the fornix and adjoining brain-substance and carrying them over to the left. Each ventricle as it is opened is to be carefully inspected and any abnormal condition of its ependyma noted. The cortex is further divided on one side, and then on the other, by holding it in the left hand and making vertical straight sections from the upper angle of the previous cut into the convex cortex, allowing the sections to fall apart, so as to avoid touching and soiling the surface with knife or fingers. Each portion thus cut represents a prism. The incisions should go well into the cortex, but not so far as to separate the different pieces. The basal ganglia are examined by means of a number of frontal sections. For this purpose the left hand is placed palm upward underneath the brain, so that as

each section is made over the tips of the fingers by one long stroke of the knife it falls forward, exposing a clean surface of which the two halves can be compared. An incision is next carried through the middle of the pineal gland, the corpora quadrigemina, and the vermiform process of the cerebellum, opening the aqueduct of Sylvius and the fourth ventricle.

Each half of the cerebellum is divided by a median hori

zontal section into halves, and these portions are still further subdivided by a series of cuts radiating from the peduncles.

In order to make sections of the pons and medulla the brain is folded together and turned over. Several crosssections are then made with the left hand placed beneath as in sectioning the basal ganglia.

Before making the sections it is well to remove the basilar and vertebral arteries, especially if they are calcified.

In Pitre's method of dissecting the brain the lateral ventricles are opened as in Virchow's method. Then the pedunculi cerebri are cut squarely across, so as to remove the pons

and cerebellum, and a longitudinal incision is carried down through the third ventricle, halving the cerebrum. Through each half of the cerebrum a series of six sections is then made parallel to the fissure of Rolando. The names of the sections and the important parts which they show are as follows:

1. The pre-frontal section through the frontal lobe, 5 cm. anterior to the fissure of Rolando, shows the gray and white substance of the frontal convolutions.

2. The pediculo-frontal section through the posterior portions of the three frontal convolutions shows the anterior extremity of the island of Reil, the lenticular and caudate nuclei, and the internal capsule.

3. The frontal section through the ascending frontal convolution, parallel to the fissure of Rolando, shows the optic thalamus, the lenticular and caudate nuclei, the claustrum, the external and internal capsules, the anterior portion of the descending horn of the lateral ventricle, and the island of Reil.

4. The parietal section through the ascending parietal convolution shows portions of the same structures as the preceding, and a transverse view of the hippocampus.

5. The pediculo-parietal section through the parietal lobe, 3 cm. posterior to the fissure of Rolando, shows the tail of the caudate nucleus in two places and the posterior portion of the optic thalamus.

6. The occipital section through the occipital lobe, I cm. in front of the parieto-occipital sulcus, shows simply the white and gray matter of the occipital lobe. The cerebellum, pons, and medulla are incised in the manner already described.

Removal of the Spinal Cord.-The body is to be placed face downward, with the head over the end of the table and a block under the chest. The incision is made over the spinous processes from the occiput to the sacrum. Dissect the skin and muscles back on each side, so as to leave the vertebral laminæ as bare as possible. The laminæ may be cut through by means of several instruments, of

which the double-bladed saw (Luer's rhachiotome) is perhaps the safest, at least for beginners. The single-bladed saw with rounded end is also very useful and can be thoroughly recommended. The operation can be done most quickly by biting off the spinous processes with the heavy bone-forceps and cutting through the lamina with chisel and hammer, but there is greater danger of injuring the cord.

The numerous artifacts in the cord, reported as neuromata and heteroplasia even within very recent times by competent pathologists, would seem to indicate that the need of careful and delicate technique in the removal of the spinal cord is not yet fully appreciated.

The lamina should be sawn nearly or entirely through in a line with the roots of the transverse processes from the third or fourth lumbar vertebra to the cervical region. The arches of the cervical vertebræ are best divided with a heavy bone-cutter, because they cannot be easily sawn, and there is sufficient room here for the points of the bone-cutter without danger of their pressing on the cord.

It is important to strike the outside limits of the spinal canal, so as to get as much room as possible for the removal of the cord. Test if the sawing be deep enough by the mobility of the spinous processes. If necessary, they can be freed by means of the hatchet-chisel and a hammer in the same way that the calvaria is loosened.

As the cord reaches only to the second lumbar vertebra, cut through between the third and fourth, free with the heavy bone-cutter the lower end of the row of the spinous processes, which are held together by their ligaments, and strip them up to the neck; then cut through the cervical arches with the bone-cutter, taking care that the point within the canal does not come in contact with the cord.

The nerve-roots are to be divided with a sharp scalpel by means of a long cut on each side of the cord. Then cut across the dura and the nerve-roots at the lower end of the exposed canal, and, while holding the dura with forceps, carefully free the cord from below up with scissors or scalpel, taking care all the time not to pull or bend the cord, be

cause in either way artifacts may be produced. Cut the cord squarely across as high in the cervical canal as possible, so that the remaining portion may be easily removed with the brain.

Lay the the cord after removal on a flat surface and incise the dura longitudinally, first posteriorly and then in front. A series of cross-sections, usually 1 to 2 cm. apart, is made through the cord while supported on the fingers during the

cutting, so that the cut surfaces shall fall apart. The different segments should ordinarily be left attached to the dura, so that their position in the cord can easily be determined.

A diagnosis from the fresh, macroscopic appearances of the cord is often very difficult to make, according to the best authorities.

The Eye.-The contents of the orbit, including the posterior part of the eye, can be readily examined by chiselling