THE DEGENERATE CRANIUM
The cranium or skull is a development in part of the vertebrae or bones
forming the backbone, and in part of dermal or membranous bones, which of
old in reptiles, as in the alligator to-day, formed the protective armour
of the skin of the head. As the head end of the spinal cord of the
lancelet developed, the cartilage enclosing it developed to protect it.
This was the earlier evolution. Later, another skull developed in
connection with this. The cranium or skull therefore has, as Minot
remarks,[188] a double origin, or, rather, there are two skulls which were
originally distinct. In evolution from the lowest fish to the highest
mammal, and in the embryonic development of man, these become united.
The primary skull, as already stated, is practically an extension of the
vertebrae, which send side outgrowths to cover the brain as the backbone
covers the spinal cord. This primary skull extended in front of the
notochord (the spinal cord of the human embryo, and the permanent spinal
cord of the lancelet), where it gave off two trabeculae cranii or front
skull plates. Behind, the primary skull or chondrocranium gives off two
occipal or rear skull plates. It gives off also two plates midway between
the trabeculae and occipitals, which, as they gradually enclose the
primitive hearing apparatus, the otocysts (permanent in fish, and
embryonic in man), are called periotic capsules. This primary skull is at
first cartilaginous, as in sharks. With the increase in the size of the
brain in evolution and in human embryology, this cartilaginous primary
skull became insufficient to roof over the brain, and thus resulted gaps
in it. The fontanelles, or soft places at the top, sides, and back of the
head of the new-born child, are the remains of this failure of the
chondrocranium, or primary skull, to cover the gains of the nervous system
in the struggle for existence. This deficiency, resultant on advance in
evolution, would have been a long-standing serious block to further
advance, were it not that the skin of the mammal retained a function
inherited from the reptiles and bony fish.
These cavities were filled by dermal bones, which, at first serving merely
as armour in the skin of the head, came to be protectors of the nervous
system. The following bones represent these dermal bones in the embryonic
human skull: The frontals, which form the chief part of the forehead; the
sutures, or dovetails, of these normally disappear in the adult, so that
the forehead seems to be but one bone. This union may not occur (Fig. 7),
as in the case of the philosopher Kant, who had a frontal suture all his
life. The dovetails are replaced by solid bone, through a process called
synostosis. In the case of the frontal bone it is normal, and in the line
of advance. Elsewhere in the skull it is often an expression of defect
which may give rise to various cranial states which are either absolutely
degenerate in type or degenerate only when occurring in certain races. The
parietals and interparietals are also dermal bones which are united by
synostosis to form the parietals or side bones of the normal adult skull.
The nasal bones which, together with the vomer, form the nose, are
likewise dermal bones, and so are the pterygoids and palatines. The
maxillaries and praemaxillaries, which, with the mandibles, form the jaws,
are dermal bones. The mandibles, however, are in part derived from the
chondrocranium.
[Illustration: FIG. 7.]
With rise in evolution, and during the progress of human embryonic
development, these bones become fewer through their early gristly union or
their synostosis. The openings in the skull resultant on the deficiencies
in the chondrocranium are larger in the sauropsida (birds and reptiles)
than in the ichthyopsida (amphibious and fish); in the monotremata
(egg-laying mammals) than in the sauropsida; in the marsupials (pouched
mammals) than in the monotremata, and in the higher mammals than in the
marsupials. The development of the brain therefore depends on the growing
and expanding power of the secondary skull formed by the dermal bones.
These, considered as bones, are degenerate from the high type of the
vertebrae, and are a mere reminiscence of that outer skeleton whereby early
fish and reptiles emulated the lobster. The influence of any check to
development such as produces degeneracy, is exerted first on the
development of the bone itself, and finally on the relation to other bones
by dovetailing.
In accordance with the general laws governing growth, deficiency in one
place is apt to result in increase elsewhere. The brain-protective
function of the dermal bones being later in development than their old
armour function, is apt to be checked by degeneracy in two ways; in the
first the bone does not grow in size or sufficiently to unite with its
fellows, or this growth occurs only for the benefit of the bone itself,
through Spencer's law of individuation, so that union with the other bones
occurs too early for the benefit of the organism as a whole. To the
factors underlying this is due the non-increase in intellect after puberty
which occurs in the higher apes, and in some of the lower races of men.
These checks also tend to the nutritional benefit of the older primary
skull, whence result the irregularities in development that constitute so
many of the stigmata of the degenerate cranium. The sutures sometimes do
not form because sufficient gristle is not produced to fill the gaps.
(Fig. 8.) These secondary gaps are often filled by new dermal bones called
Wormian. Sometimes this deficiency coexists with too early synostosis
elsewhere.
[Illustration: FIG. 8.]
Degenerate skulls have therefore been divided from the standpoint of these
various unions (by synostosis or otherwise) and non-unions of the sutures,
on the principle that premature synostosis of a suture produces shortness
of the diameter, perpendicular to the direction of the obliterated
suture.[189] The bones stop growing prematurely at the seat of the
synostosis, but the unaffected borders continue growing. The following
types result on this principle:
[Illustration: FIG. 9.]
I. Simple macrocephaly (largeness of head). (_a_) Hydrocephaly (water in
the head. Fig. 9.) (_b_) Kephalones (all heads. Fig. 10), without
hydrocephaly. These two conditions result from the inability of the dermal
bones to fill at the proper period the gaps in the chondrocranium. Neither
of these denotes complete intellectual degeneracy on the one hand, nor
vast intellect on the other. Cuvier was a case of healed-up hydrocephalus,
whence his large brain and skull. In a case of kephalones observed by
Kiernan there was a brain-weight of 68 ounces. The patient was an
imbecile, practically unteachable.[190] Both these conditions denote deep
degeneracy, which, however, may find expression elsewhere than in the
moral sense or intellect.
[Illustration: FIG. 10.]
[Illustration: FIG. 11.]
II. Simple microcephaly (smallness of head. Fig. 11) or nannocephaly
(dwarf head). As a rule these are found among idiots, but much has been
done by training, even for them. Many seemingly great intellects, however,
have heads approaching, if not reaching this type.[191] Des Cartes,
Foscolo, and Schumann had sub-microcephaly. The poet Shelley had a head
belonging very nearly to this category, but while he exhibited many
stigmata of degeneracy, that of intellectual deficiency was wanting. This
type of skull, however, is usually associated with deep degeneracy. It
represents in man the condition underlying the premature suture-closing
which occurs in the ape. It sometimes may exist with considerable
intellect, as in the case of Donizetti. Sometimes this suture-closing
directly prevents brain growth. This condition is rarer than many surgeons
admit, but it does occur, as witness the cases of Vico, Malebranche, and
Clement VI. The fact that these three fractured their skulls in infancy
saved them from being imbeciles and idiots like their brothers, sisters,
and cousins.
[Illustration: FIG. 12.]
III. Dolichocephaly (long-headedness. Fig. 12). (_a_) Upper middle
synostosis. (1) Simple dolichocephaly is due to synostosis of the
sagittal, or antero-posterior suture of the skull. Whether this be due to
degeneracy or not depends entirely on the race in which it occurs. The
ultra-dolichocephaly of Daniel O'Connell was due, in Kiernan's opinion, to
his birth in an Irish district settled by dolichocephalics. Undoubtedly
dolichocephaly is tending to mesocephaly (medium size of head). Even the
negro, generally regarded by ethnologists as dolichocephalic, is tending
in this direction, as numerous observations of my own show.
Dolichocephaly, however, while it does not demonstrate, suggests
degeneracy, since it seems to be a disappearing type of skull. The changes
in American families in this particular indicate this. (2) Sphenocephaly
(wedge-shape of head. Fig. 13) is due to synostosis of the sagittal
suture, with compensatory growth in the region of the large fontanelle.
(_b_) Dolichocephalic states, resulting from inferior lateral synostosis
are: (1) Leptocephaly (narrowness of head), due to synostosis of the
frontal and sphenoid bones. (2) Klinocephaly (saddle-shaped head) is due
to synostosis of the parietal bones with the greater wings of the
sphenoid, or of the parietal with the squamous portion of the temporal
bone.
[Illustration: FIG. 13.]
[Illustration: FIG. 14.]
IV. Brachycephaly (shortness of head. Fig. 14). The pure type like pure
dolichocephaly is not necessarily by itself evidence of degeneracy, as it
may represent race. It is, however, a disappearing type of skull, and
hence should lead to critical examination. In the case of the philosopher
Kant his ultra-brachycephaly could not be charged to race, since he sprang
from dolichocephalic Scotch on one side and dolichocephalic Germans on the
other. (_a_) Posterior stenosis. (1) Pachycephaly (thickness of head) is
due to synostosis of the parietal bone with the occipital. (2) Oxycephaly
(sugar-loaf head) is due to synostosis of the parietal bones and the
occipital with compensatory growth of the region of the anterior
fontanelle; a variety of this is acrocephaly (spire head). (_b_) Upper,
anterior, and lateral synostosis. (1) Platycephaly (flat head. Fig. 15),
or chaemacephaly, is due to extensive synostosis of the temporal bones with
the parietal. Kant, in addition to his cranial stigmata, had this
condition. (2) Trochocephaly (roundness of head) is due to partial
synostosis of the frontals and parietals in the centre of the coronal
suture. (3) Plagiocephaly (wry head. Fig. 16) is due to unilateral
synostosis of the frontal and parietal bones. (_c_) Brachycephaly due to
inferior medium synostosis. Simple brachycephaly is due to early
synostosis of the nasal and sphenoid.
[Illustration: FIG. 15.]
To these should be added kyphocephaly (lump head), due to synostosis of
the posterior part of the squamous portion of the temporal and the
parietal bones with Wormian bones in the lambdoid fissure. Tapeisocephaly
(low head) is due to synostosis of the great wings of the sphenoid with
the frontal. Scaphocephaly (boat-shaped head. Fig. 17) was a term applied
by Von Baer to skulls which are very narrow and compressed at the sides,
and in which there is no trace of the sagittal suture, but its region is
so elevated that the skull cap has the form of a keel boat bottom upward.
Trigonocephaly (triangular head) is a variety of scaphocephaly in which
depression occurs in place of the keel. Sir Walter Scott had a skull in
which premature closure of the sagittal suture produced the appearance of
scaphocephaly, but compensation for this elsewhere produced a decidedly
different type. Scott presented neurotic phenomena during youth, albeit
the brain disease from which he died had anything but a degenerate origin.
[Illustration: FIG. 16.]
[Illustration: FIG. 17.]
Morton and Catlin claim that while the artificial distortions of the
cranium may play a part in developing synostosis these have no effect upon
the intellectual functions. It has been stated further that there are no
mental data to show the effect of artificial malformation of the child's
head during development. Frederick Peterson expresses the opinion that
this practice only exists among the lower races of mankind. In this he is
in decided error, since, as Barnard Davis pointed out many years ago, the
practice is far more widespread than is usually suspected. It was common
all over Europe, was practised by the Turanians, by the Slaves, by the
Scandinavians, Anglo-Saxons, and Celts. Less than half a century ago
Foville[192] proved that the nurses in Normandy were still giving
children's heads a sugar-loaf shape by bandages and a tight cap. In
Britanny they preferred to press it round. In those districts Foville
found that not only congenital cranial irregularities of all types, but
epilepsy, idiocy, and insanity were exceedingly frequent. As customs like
these survive in folklore long after the original superstition which gave
them birth, it is exceedingly probable that such crop out in descendants
of these races to the present day, to confront the anthropologist with
some remarkable crania. Tylor[193] is of opinion that without respecting
the repressive action of the Government, the Bretons and Normans secretly
continue this practice. Despite the labours of Foville these people openly
defied the Government for ten years.
Certain conditions of the occiput have been described as associated with
degeneracy. As Obici[194] and Dei Vecchio[195] have shown, the occipital
condyle, in man normally convex, abnormally varies between two extremes,
the flat and angular condyles. The flat condyle indicates a degenerative
type. In the angular condyle the anterior face is derived from that
portion of the basi-occipital nucleus that normally takes part in the
formation of the anterior condyle region; the posterior face forms the
embryonal germ of the occipital.
The occipital of the adult is the final outcome of the fusion of an
uncertain number of vertebrae. The occipital bone in man is practically
made up of five bones, union between which does not occur completely until
the fifth or sixth year. The deficiencies in the chondrocranium appear in
the occipital bone, which requires a small portion of the dermal bone to
complete it on each side.
The variability of the occipital bone which, as just shown, is so
frequently associated with all forms of degeneracy, is still better
understood when we remember that it is of vertebral character. The
investing mass of the head and of the notochord is the skeleton of the
occipital bone. Between this skeleton and the pituitary body the important
portion of the brain formed by the occipital lobes takes its origin. As
these lobes are practically, as Spitzka has shown, the great centres of
sense and other inter-associations it is not astonishing that their
imperfect development should be accompanied by changes in the occipital
bone. As Crochley Clapham, Mickle, and Spitzka have shown, a flat occiput
is common in imbecility and moral insanity. It has been found quite
frequently in "reasoning maniacs" by Campagne. The proper development of
the occiput influences the proper development of association tracts which
serve as a balance wheel to the individual. The proper development of the
occipital bone is, moreover, connected with the proper development of the
two last vertebrae, which like it are losing their vertebral
characteristics.