horizontal slice has been taken at the level of the corpus callosum.
The lateral ventricle (i.e., the hollows of the hemisphere) is not yet
opened. A lower cut (Figure 3) exposes this (V.L.). The level of these
slices is approximately indicated in Figure 1 by the lines A and B.
This latter figure will repay careful examination. The arrow, ar.,
plunges into the third ventricle, behind the great middle commissure
(m.c.), and the barb is supposed to lie under the roof of the
mid-brain, the corpora quadrigemina (c.q.). The position 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.