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308

Cunningham Memoirs.

an invariable rule to take measurements of relative positions of angles only
in preparations in which the brain has been hardened in situ by suitable
injection, and yet in the large majority of cases this simple precaution has
not been observed.

Of all the procedures that have been devised, and are enumerated in the
Bibliography, none is so accurate as that adopted by Professor Cunningham
, namely, hardening the brain in situ, removing the bones of the
cranium piecemeal, and finally taking an accurate cast of the whole preparation
for the better investigation of the topographical details of the
specimen. I have twice enjoyed the opportunity of working with such
material in his laboratory, and with the aid of his very generous
assistance.

Of the remaining methods (vide Bibliography), unquestionably those
which are designed to express the facts by relative measurement are by far
the most valuable, and of them should be selected, as the foremost, the
procedure of Mtiller and the later method of Zernoff (see especially Altou-
khoff). Both are capable of very valuable and trustworthy extension.

So far, therefore, these three anatomical methods afford promise of
exact results when carried out on the lines above mentioned.

Turning now to the considerations of the localization of function, which
in this connexion cannot be disregarded, it is only necessary to draw
attention to the fact that the cortex of the excitable region (t. e. the
central gyri, &c.) must, I believe, be regarded as theoretically divided
by lines which are parallel with the margin of the hemisphere, and which,
where coincident with the frontal sulci continue the direction of these
across the fissure of Rolando into the parietal lobe. Clearly, therefore,
it must be the particular object of future research to give reliable data
for determining the position of points in lines drawn vertically, or,
speaking more correctly, at right angles to the middle line, the longitudinal
fissure.

Fortunately the anatomical configuration of the hemisphere and sulci
lends itself essentially to the furtherance of this object, and only the
accumulation of facts are needed to supply the required information.

In the following summary of the principal facts known on this subject