But SWEDENBORG was not satisfied with knowing only that the psychical
functions arise within certain regions of the cortex of the large
anterior region of the cerebrum: but he continued his search for their
inmost origin, and thus he came to the conviction that the _psychical
processes in reality result from the joint work which is performed by
the minute cortical elements_, which SWEDENBORG called ›_Sphaerulae_› or
›_Cerebellula_›, that is, the same bodies which we now call the _cortical
nerve-cells_. These were the units of which the brain was in reality
composed and out of which its actual esse was derived. (See ›The Brain›,
No. 34). It was to these ›Cerebellula› that the sensory impressions went,
and in these they were perceived and brought to consciousness; it was
in these that conceptions, thoughts, judgments, conclusions, came into
being. (Œc. R. A. II., No. 191, and ›The Brain›, No. 98). And this was
possible because there were as many kinds of ›Cerebellula› as there were
kinds of sensory impressions, and that these ›Cerebellula› were connected
together into groups with different subdivisions. (Œc. R. A. II., No.
193; VII., chap. XX.). It was also from the ›Cerebellula› of the cortex
that the determinations and impulses to the various movements of the
body emanated. (›The Brain›, No. 99). And this was possible because the
›Cerebellula› cohered each with its own nerve-fibril, which in their turn
innervated the muscle fibre, and that the ›Cerebellula› were _arranged
into groups, these into greater groups, these into convolutions (gyri)_,
etc., corresponding to muscle fibres, muscles, groups of muscles, etc.
(Œc. R. A. II., Nos. 146, 156, and ›The Brain›, No. 99). And it is in
this connection that SWEDENBORG _refers to experiments on animals by
which it might be shown which gyre or part of convolution it is, which
answers to this or that muscle in the body_.[80]
How SWEDENBORG was able to come to this modern conception ought not to be
so exceedingly difficult to understand if we summarize what was already
known at that time about these cortical elements and add thereto the
conclusions as to the functions of the cortex to which SWEDENBORG had
already come.
In SWEDENBORG’s time the conception of HIPPOCRATES of the brain as a
gland was still generally received. In this one had, however, as MALPIGHI
says, ›since the time of PICCOLOMINEUS› learned to distinguish between an
outer, greyish layer, ›cerebral cortex›, and an inner, more pure white
mass, the ›cerebral medulla›.[81]
Through the microscopic investigations of LEEUWENHOEK (1632-1723) it had
further been discovered that the substance of the brain (especially of
the cortex) contained, besides a great mass of blood-vessels and very
fine fibres, _a numberless mass of_ peculiar _small bodies_ of varying
size, by him called ›globuli›, connected with the vessels and fibres.
(See Œc. R. A. II., Nos. 71-75, 112, etc.).
MALPIGHI, (1628-1694), had closely examined these ›globuli› and described
them as small oval or polygonal ›glands›, which were closely surrounded
by blood-vessels, and in _their inner central ends sent forth processes
forming vessel-like fibres which continued into the cerebral medulla_.[82]
As these fibres or vessels formed small clusters, the little glands
hanging on their extreme ends, like ›dates on their stems›, as MALPIGHI
expresses it, thus formed _small groups_.
Within these groups the cortical elements were, however, _well isolated
from each other_ by clefts, which indeed sometimes were very small, but
could nevertheless be plainly demonstrated with the aid of colouring
matter.[83]
The cortical elements taken together formed the winding groups which on
the surface of the brain gave rise to the so called gyres.[84]
The profusion of blood-vessels, as was said, LEEUWENHOEK and MALPIGHI
had already described as being very great, but RUYSCH (1638-1731) had
afterwards by his famous vascular injections found it to be so great
that he would not call the cortex a glandular but actually a ›vascular›
tissue. (Œc. R. A., II., No. 86). Because of the enormous wealth
of blood-vessels there was thus carried to the cortical substance,
especially to the little follicles, a plenteous quantity of blood,
and from this, according to the opinion of that day, the most subtile
components of the blood could pass to the cortical elements and thereby
be transformed into ›spiritus animalis›. And finally, the Italians
BELLINI, (1643-1704), and ZAMBECCARI had shown by their analyses that the
juice of the brain possessed a highly subtile composition, above all a
great volatility and lightness, and was exceedingly mobile. (See Œc. R.
A. II., Nos. 88, 96, 119). All this SWEDENBORG has himself quoted in his
works.
On the basis of these and some other anatomical and physiological data,
in conjunction with a number of clinical and experimental observations,
SWEDENBORG, as we have before seen, came to the conclusion that it is in
the _cortex_ that the soul’s activity comes into being; but at the same
time he concluded that, strictly speaking, the cortical elements were
the real work-shops. For he reasoned in the following manner: When the
sensory impressions enter the brain, they certainly proceed no further
than to the _›Sphaerulae› of the cortex, since these constitute the
beginnings of the nerve and medullary fibres_: were they to go further,
for instance to the small arteries which surround the cortical elements,
or to the membranes of the brain, then they would overstep the boundary,
as he says, and leave the actual centre and go out to the more peripheral
parts.[85]
SWEDENBORG consequently here followed the same line of thought as his
predecessors. DESCARTES supposed that the nerves originated from the wall
of the central ventricle of the brain and therefore located the images of
sensory impressions, etc., there. VIEUSSENS and others thought that the
nerves originate from the centrum ovale, and thus he placed the psychic
activity there. And SWEDENBORG now proceeded in a similar manner when he
attributed the psycho-sensory operations to the ›Cerebellula›. And what
other parts of the cortex were better fitted to perform the demanding
and ever-shifting psychical labour than the ›Cerebellula›, to which the
life-giving powers of the blood were so plentifully admitted, and in
which, according to the testimony of many, the highly subtile nervous
fluid was created, whose office it was to communicate the rapid and
shifting utterances of the soul’s life!
SWEDENBORG’s predecessors had thought that the distinctions between
the sensory impressions depended partly upon what kind of nerve was
affected, and VIEUSSENS had located the images of perception and memory
in the nerve-tubes in the centrum ovale, which had the finest caliber.
What, then, was more natural than that SWEDENBORG should now locate
these images in the ›Cerebellula› of the cortex? For what substance
of the cortex was better fitted, a more suitable medium to comprehend
and distinguish the innumerable shades of the impressions than these
myriads of ›Cerebellula›—of different sizes, forms and consistency,
etc., which were connected each with its own special nerve-fibril and so
well distinguished from their neighbors! And at the same time they were
connected with the other ›Cerebellula› into groups of different kinds, by
which the psychical elaboration of the impressions was made possible.
On similar grounds SWEDENBORG supposed that the psycho-motor labour was
performed by the ›Cerebellula›, from which the nerves derived their
origin. And here we may recall that VIEUSSENS had already _connected
certain groups of nerves with certain bundles of medullary fibres_, and
that MALPIGHI had shown how _bundles of fibres of the cerebral medulla
corresponded to smaller and larger groups of cortical elements_, each
one of which, hanging by its fibre, formed the different _gyres of
the brain_. If we consider this, then we can easily understand how
SWEDENBORG, with his view of the cortex, could divine the correspondence
between the components of the convolutions and the muscles.
It is interesting to here follow him in his line of thought and to
see how well he understood how to combine his anatomical and clinical
experiences: With the magnifying glass one can see how the nerve-fibres
spring forth from the cortical substance like a brook from its source;
if now the cortical substance be injured (as in the case of certain
brain diseases, and which one may clearly see upon autopsy), then the
injury is spread through the nerves connected with the cortex and at
last all the way down to the muscles, and that, he thought, explained
the motor disturbances.[86] And further ... when one or several of the
›Cerebellula› of the cortex are destroyed, then the damage is spread more
immediately only to their proper nerves and muscles.[87]
In this manner did SWEDENBORG synthesize his anatomical,
pathological-anatomical and clinical experiences and extracted from
them his conclusions, and by them he arrived at essentially the same
conception, as our times, of the principles of the nervous system, its
cellular structure. He did not indeed employ the same nomenclature for
the nerve-cells and their long processes, as we do; but the matter
itself: the nature of the nerve-cells as elementary organs of the nervous
system, the intimate connection between the nerve and its cell-body,
indeed even its dependence upon it in regard to nourishment, etc., he was
able to clearly grasp in this way,—and this more than a century before
our modern theory of these relationships, the ›neurone-theory› saw the
light.