Freiburger historische Bestände - digital

vi

Cunningham Memoirs.

Further, the facts acquired in this manner have been compared,
checked, and amplified, by the evidence afforded by ontogeny. It must be
admitted, however, that in the case of the primate brain this evidence
is somewhat one-sided. Very little is known of the manner in which
the fissures and gyri make their appearance in the foetal ape. In so far
as the human brain is concerned the material is very abundant, but the
picture afforded is so variable that very different interpretations may
be arrived at by different observers. It cannot be too strongly insisted
on, that it is only by the close study of large numbers of developing
brains in each stage of growth that correct and trustworthy information
can be gathered; and seeing that the development of the permanent
fissures is for the most part compressed into the last four months of
intra-uterine growth, there should be little difficulty in meeting this
requirement.

It was my intention when I began this investigation to make a special
study of the entire cerebral surface of the primate brain; and taking up
each fissure and gyrus in turn, I had purposed tracing its history through
every stage of its development and growth. I very soon ascertained,
however, that such a task would require many years to accomplish,
and, as it was necessary to produce this Memoir within a reasonable
time, I was reluctantly obliged to abandon my original plan of work. I
have therefore restricted my investigations to certain of the more important
fissures, but I have endeavoured to elucidate the anatomy of these
from every point of view—the morphological as well as the topographical.
In the pursuance of this inquiry the questions which I have specially
sought to determine are the following:—

1. What is the more usual mode of development of the selected fissures ?
At what period of life do they attain their fully-formed condition, and
what light does the whole process of furrow-formation throw upon questions
relating to the general growth of particular areas of cerebral cortex ?

2. Do the fissures undergo any change of position on the cerebral
surface after they have once been laid down; and are the changes which
we know occur in the relations between the fissures and the cranial sutures
at different periods of growth produced by an increase or a decrease of