of ar. is also
indicated in Figure 1. Before reading on, the beginner should stop a
while here; he should carefully copy or trace our figures and, putting
the book aside, name the parts, and he should then recopy, on an
enlarged scale, and finally draw from memory, correct, and again
draw. By doing this before the brain is dissected a considerable
saving of time is possible.

Section 124. Proceeding from the brain are twelve pairs of cranial
nerves. From the fore-brain spring two pairs, which differ from the
rest of the cranial nerves in being, first of all, hollow outgrowths of
the brain-- the others are from the beginning solid. The first nerve is
the olfactory lobe, which sends numerous filaments through the
ethmoid bone to the olfactory organ. The second is the optic nerve,
the visual sensory nerve.

Section 125. The mid-brain gives rise to only one nerve, the third,
which supplies all the small muscles of the eye (see Section 114),
except the superior oblique and external rectus.

Section 126. The remainder of the nerves spring from the hind-brain.
The fourth pair supply the superior obliques, and the sixth the external
recti; so that III., IV., and VI. are alike purely motor nerves, small and
distributed, to the orbit. The fifth nerve, the trigeminal, is a much
larger and more important one; it is a mixed nerve, having three main
branches, of which the first two are chiefly sensory, the third almost
entirely motor; it lies deeply in the orbit. V1 (see Sheet 9) runs up
over the recti behind the eyeball, it is the ophthalmic branch; V2, the
maxillary branch, runs deeply under the eyeball and emerges in front
of the malar, and V3, the mandibular branch, runs down on the inner
side of the jaw-bone to the jaw muscles and tongue.

Section 127. If the student will now recur to the figures of the dog's
skull (Sheet 6), he will see certain apertures indicated in the cranial
wall. Of these, o.f. is the optic foramen for the exit of nerve II.,
perforating the orbito-sphenoid. Behind this there comes an irregular
aperture, (f.l.a.), the foramen lacerum anterius, giving exit to III., IV.,
VI., and V1. V2 emerges from the foramen rotundum, and V3 from the
foramen ovale, two apertures uniting behind a bony screen.* Just in
front of the bulla is a foramen lacerum medium (f.l.M.), through which
no nerve passes.

* In the rabbit's skull f.l. anterius, the foramen rotundum, and
foramen ovale are not distinct, and ther