Freiburger historische Bestände - digital

216

Cunningham Memoirs.

sulcus postcentralis inferior which, in this case, is developed as a separate
element.

Now that we have considered the five different varieties of the intra-
parietal sulcus and noted the frequency of each at different periods of life,

Fig. 43.—From Sernoff, and reproduced by the kind permission of the author. Illustrates Variety V.

of the intraparietal sulcus.

there are certain deductions which may fairly be drawn from the facts
detailed:—

1. In man there appears to be a general tendency towards a union of
the two originally distinct postcentral elements of the sulcus and a divorce
from the lower of these of the ramus horizontalis, which in its phylogenetic
history is clearly continuous with, and in reality a part of it.

2. In the cerebral hemispheres taken from the foetus and young child,
we notice a greater number of cases in which one or more of the elements
of the sulcus are separate and distinct from the remainder of the furrow
than in the case of adults. This indicates that in certain cases union of
these parts of the sulcus is delayed until the earlier part of childhood.

3. The discrepancies which exist between the percentages obtained by
Sernoflc for the Russian brain and those obtained by me for the Irish brain
render it possible that in the arrangement of the different parts of the intraparietal
sulcus we may ultimately be able to point out racial distinctions
by a more extended study of this furrow-group.