Freiburger historische Bestände - digital

138

Cunningham Memoirs.

above the suture on the right side. In a child two years and two months
old the fissure was 14 mm. above the suture. Symington is of opinion
that the fissure and the suture "begin to approach each other soon after
the end of the second year, and that they gain their permanent positions
by the eighth or ninth year. Thus, in a well-developed boy, five years
old, the fissure was only about 5 mm. above the anterior part of the
suture, while in a girl, nine years of age, they were practically at the same
level." He believes, however, that the process may be delayed.

In the main we may consider that the conclusions which have been
arrived at by Symington are correct, but it must be noted that the process
is one which is subject to great variation. In Plates v. and vi. the relations
which are presented by the Sylvian fissure and the squamo-parietal suture
are exhibited in a series of heads at different periods of growth. If we
compare figure 5, which represents the head of a girl six months old, with
figure 4, the head of a girl one year old, we observe that in the older
specimen the distance between the suture and the fissure is both relatively
and absolutely greater than in the younger specimen. In the former it
is 21 mm., whilst in the latter it is 16 mm. Again, in figures 6 and 7 are
exhibited the heads of a girl and a boy of four years old. In the former
the fissure has nearly attained the adult position with reference to the
suture, being only 4 mm. above it, whilst in the latter it is still 14 mm.
distant from it. Again, little progress is shown in figure 8, a boy of five
years old, where the suture is still 14 mm. below the fissure. Then when
we come to figures 9, 10, and 11, which are drawings of the heads of a
girl of eleven, a boy of twelve and a-half, and a youth of fifteen, we reach
a condition which is very common in the adult. Still it is noteworthy that
in all of these the fissure is still above the level of the suture, whilst in the
adult we may meet with it above, subjacent to, or below the suture.

But all conclusions which rest simply upon absolute results are unsatisfactory
. We can only obtain a proper conception of the true position of
the Sylvian fissure and of the changes which this undergoes on the surface
of the cerebrum, and in reference to the cranial wall by the conversion of
absolute into relative results. The relative position which the Sylvian
fissure occupies at different periods of life has not hitherto been determined.