Chapter II: Craniology (2)

These constitute, as it were, two centres, beyond which, on this side and on that, we may picture to ourselves the _individual variations_ drawn up in martial line. In this case, the space between 75 and 80, in other words, the limits of mesaticephaly, may be interpreted as due to oscillations between dolicho- and brachycephaly according to the laws of variability, which is analogous to what takes place in the case of oscillations in the opposite direction (70-75 dolichocephaly; 80-85 brachycephaly). From this point of view, these two numbers, 75 and 80, constitute _median centres_ of two different types.

But according to Broca and his school--and this view is accepted by many anthropologists--mesaticephaly should be regarded as constituting a _fusion_ of the two other types, the brachy- and dolichocephalic, whence it follows that mesaticephalics would be _hybrids_. Other authorities, on the contrary, exaggerating the conception of the fixity of the cephalic index in a given race, admit the existence of mesaticephalic races.

But it has been observed that the greater number of mesaticephalics are to be found in regions where dolichocephaly prevails; in certain districts of Africa, as for example, in Somaliland, not a single brachycephalic exists, yet none the less the mesaticephalics are numerous. Accordingly, mesaticephaly may be classed with _dolichocephaly_ and regarded as one of its variations, while it seems to be independent of brachycephaly. Therefore the nomenclature of Retzius may for many good reasons be chosen and adopted in our schools. In conclusion, we shall regard the brachycephalics and dolichocephalics as the two fundamental types; and shall adopt the figure 80, included among the brachycephalics, as the limit of separation. The different grades of dolicho- or brachycephaly are to be determined by _mean averages_, and the oscillations due to individual variations, by _series_.

Hence it is important to determine the _mean average_ and the oscillation of the cephalic index for the different races; and this is of interest to us as educators, in order to establish the limits of _normality_.

The practical method of studying the cephalic index is according to geographical distribution.

Here are a few general data of the cephalic index relative to its distribution:

The most dolichocephalic of all peoples are found in Melanesia, Australia, India and Africa. In the Fiji Islands the mean cephalic index is 67; in the Caroline Archipelago it is 69; in various regions of India, 71; that of the Hottentots, 74; of the Bantus, 73. Belonging to the dolichocephalics or mesaticephalics are the populations of the extreme south of Europe (Mediterranean race) and at the extreme north (English, Scotch). On the contrary, the races of western Europe and of central Asia are brachycephalic (Celts, Mongols). The most brachycephalic of all these peoples are met with in the Transcaucasus; their mean average is 88.7. There also exists a notable brachycephalic type in France (Savoyards, 86.9; inhabitants of the upper Loire, 87.4); also in Dalmatia, 80, while the Lapps of Scandinavia are also ultrabrachycephalic, 87.4.

On very general lines, it may be said that the dolichocephalics are the Eurafrican races (including the Mediterranean race, with which the first civilisations are associated: Egyptian, Greek and Roman) who migrated from the Mediterranean basin into Europe; and the brachycephalics are the Eurasian races, who on the contrary migrated from continental Asia across western Europe (the Aryans).

As far as regards Italy, its population is by no means evenly constituted. The median index given by Livi for Italy, deduced from observation of more than 29,000 subjects is 80; in regard to regional distribution, the results are shown in the following table:

Piedmont 85.9
Emilia 85.2
Venctia 85.0
Lombardy 84.4
Umbria 84.1
Marches 84.0
Liguria 82.3
Tuscany 82.3
Campania 82.1
Abruzzo and Molise 81.9
Latium 81.0
Basilicata 80.8
Apulia 79.8
Sicily 79.6
Calabria 78.4
Sardinia 77.5

Let us remember that if the cephalic index were measured directly from the cranium, the result would be one or two units less, hence the mean average of the cranial index would be about 78.

The accompanying map represents still more clearly the geographical distribution. The results show that in Piedmont, in Emilia, and in Northern Italy in general the inhabitants are more brachycephalic; while in the south and more especially in the island possessions we find the more dolichocephalic part of the population. The highest degree of dolichocephaly is found in Sardinia.

But if, instead of the cartographic summary herewith reproduced, we could examine the exhaustive one with which Livi has illustrated his great work on Anthropometry, we should discover that the distribution does not follow the great _regional lines_; but that as a matter of fact certain _human groups_ exist, isolated like little islands, which have a cephalic index in marked contrast to that of the remaining population of the same region.

Thus, for example, at Lucca, in the midst of a brachycephalic population, there is a pronouncedly dolichocephalic group; and in the midst of the dolichocephalic population of Abruzzo and the neighbouring provinces, there exists at Chieti a strongly brachycephalic group. Besides these and similar groups contrasting with the regional type, there exist a multiplicity of differences, from one successive boundary line to another, so that the _limits_ _of the cephalic index_ may be determined with great minuteness in the various regions.

Livi's large charts lend themselves with great clearness to this sort of analytical study, which would be found to be very profitable to teachers.

It is also quite instructive to compare the different charts representing various anthropological data of ethnical importance; such, for example, as that of the distribution of stature and that of the distribution of pigmentation. These data are regarded by anthropologists as attributes of race. Well, in these three charts it is evident at the first glance that there is a notable resemblance in distribution, so much so than an eye untrained to observation would be likely to confuse them. The cephalic index, the stature, the colour of the skin are consequently of almost uniform distribution. Corresponding to the most pronounced brachycephaly, we have the tallest stature and the fairest complexion; corresponding to the most pronounced dolichocephaly, we find instead the lowest stature and the most brunette types. Such an accumulative coincidence, in certain communities, of characteristics, in contrast to those that are found combined in certain other communities, reveal the existence in Italy of _two different races_. One of these races seems to have descended from over the Alps; the other, to have landed on the shores of the Mediterranean. The first belong to the Eurasians; the second to the Eurafricans.

In my work upon the population of Latium, the mean cephalic index obtained by me is 78. The distribution according to the localities studied affords the mean averages noted in the following table, in which I have also recorded the maximums and minimums, and the percentage of brachycephalic and dolichocephalic individuals who contributed to the given means:

CEPHALIC INDEX AMONG THE PEOPLE OF LATIUM
(ACCORDING TO MONTESSORI)

--------------------------------------------------------------------
|Mean | | | Dolicho- |Brachy-
Provinces |cephalic |Minimum |Maximum |cephalics, |cephalics,
|index | | |per cent. |per cent.
----------------+---------+--------+--------+-----------+-----------
Rome | 78 | 73 | 89 | 63 | 37
_Castelli Romani_ | 76 | 70 | 79 | 100 | --
Tivoli | 80 | 76 | 87 | 59 | 41
Velletri | 79.5 | 75 | 86 | 50 | 50
Frosinone | 80.7 | 75 | 87 | 43 | 57
Civitavecchia | 78.5 | 78 | 80 | 65 | 35
Bracciano | 77 | 75 | 80 | 65 | 35
_Orte_ | 83.6 | 75 | 90 | 11 | 89
Acquapendente | 79.4 | 76 | 81 | 60 | 40
--------------------------------------------------------------------

The results show a preponderance of brachycephalics or of dolichocephalics in the places where the mean cephalic index is respectively highest for brachycephaly (Orte) or for dolichocephaly (Castelli Romani). Furthermore, the extreme maximum and minimum figures are found to be included in these groups (90 at Orte and 70 at Castelli).

It should be noted that at Castelli Romani the mean average is mesaticephalic (76), notwithstanding the absence of brachycephalics; this average is based on figures showing an extremely pronounced dolichocephaly (ranging to 70!). The groups at Castelli and at Orte also showed characteristics in respect to stature (see page 111); at Orte the mean stature is 1.61 m., with a maximum of 1.70 m. (very tall statures for women), and at Castelli the mean stature is 1.47 m., with a minimum of 1.42 m. (low statures).

Similarly, in regard to pigmentation, I found at Orte a prevalence of blonds, and at Castelli of brunettes. Hence the conclusion may be drawn that at Castelli and at Orte there exist groups of human beings who are of almost pure race, in the midst of a population in which racial types have become attenuated or hidden; but in centres like these we still find persistent testimony as to the ethnic factors that combined to form the people of Latium: the one, a blond, tall, brachycephalic race; the other, dark, small, and dolichocephalic.

_The Cephalic Index at Different Ages of Life._--Another quality that renders the cephalic index of great importance is that it remains constant in the course of growth, since the two maximum diameters, the antero-posterior and the transverse, increase at very nearly the same rate, excepting during the earliest years, at which time the length of the cranium increases slightly more than the width. According to some authorities it is in the second year, according to others it is in the fourth or seventh, that the cephalic index becomes constant (Binet, Deniker, Pearson, Fawcette, Ammon, Johannson, and Westermarck).

The following table is one that I have drawn up on the basis of Quétélet's figures:

CEPHALIC INDEX

---------------------------------------------------
Age | Males |Females| Age | Males |Females
---------+-------+-------+---------+-------+-------
At birth | 83 | 83 | 11 years| 80 | 79
1 year | 80 | 80 | 12 years| 80 | 79
2 years | 80 | 80 | 13 years| 80 | 79
3 years | 80 | 80 | 14 years| 80 | 79
4 years | 79 | 79 | 15 years| 80 | 79
5 years | 79 | 79 | 16 years| 80 | 79
6 years | 79 | 79 | 17 years| 80 | 79
7 years | 79 | 79 | 18 years| 80 | 79
8 years | 79 | 79 | 19 years| 80 | 79
9 years | 80 | 79 | 20 years| 80 | 79
10 years | 80 | 79 | --- | -- | --
---------------------------------------------------

Since it has been observed that the cranium in the course of its growth may assume forms, amounting even to apparent malformations (due chiefly to "bumps," either symmetrical or asymmetrical), which disappear during the evolution of the individual, the _cephalic index_, for _the very reason_ that it does not represent a faithful description of the form, gives us precious aid in judging the cranium of the child, because it _accurately determines the proportions_ _between length and breadth_ which are destined to persist even in the adult, and hence serve to give, even in infancy, a sure indication of the ethnic type to which the child belongs.

Negro Children
Children born in Syria
Children born in Russia
Children born in Germany

FIG. 74.]

We owe to Dr. Ales Hrdlicka the extremely important graphic chart, which I will proceed to summarise, of the cephalic indices of children of various races: the central dotted line corresponds to the index 80: consequently the brachycephalics are indicated on the right, and the dolichocephalics on the left (Fig. 74).

In the case of Italy, the graphic line extends between the two extreme figures of 70 and 90, which are precisely the extreme limits that we have already noted for individual adults, in the case of the women of Latium: moreover, the curve is perceptibly symmetrical, although the brachycephalics are in the majority; a fact already established by Livi's mean averages. One might say that this curve was a graphic representation of Livi's two-colour method in his map of the cephalic index: one-half of Italy is brachycephalic and the other half is dolichocephalic; but since brachycephaly prevails in the northern half, a wider extent of territory is occupied by brachycephalics.

In America, where emigration brings every variety of humanity, the curve is even more symmetrical, and rests on a broader basis, representing widely separated extremes. Ireland also shows a very perceptible symmetry, the population being a mixture of Celts (brachycephalics) and of Scotch (northern blond dolichocephalics).

In Germany there is a prevalence of brachycephalics; we are here approaching the eastern regions from which the Eurasian race came through emigration. Here the Slavs and Celts (brachycephalics who immigrated into Europe at various epochs) are intermingled with a notable percentage of dolichocephalics (Teutons).

Children born in Ireland
White Children born in America
Children born in Italy

FIG. 74.]

But in Russia, a region still further east, and similarly in Syria, we find an almost pure race: the curves lie wholly within the field of brachycephaly.

On the contrary, the dark-skinned children given in the last chart, and belonging to African races and tribes of American Indians, are all of them _dolichocephalic_.

According to Binet and other writers, the _cephalic index_ and the _cranial volume_ are the two anthropological data on which the criterion of _normality_ of children's heads must be based.

When we observe a child's head which is apparently malformed, we cannot call it _abnormal_; it is not abnormal unless it has a volume notably too small (submicrocephaly, microcephaly) or too large (rickets, hydrocephaly); and a cephalic index exceeding the normal limits, in other words, _exaggerated_ (scaphocephaly, trochocephaly, pathological brachycephaly occurring in hydrocephalics).

THE VOLUME OF THE CRANIUM

The volume of the cranium owes its importance, as we have already seen, to the fact that the cranium represents the _envelope_ of the brain, and is consequently normally determined, as regards its dimensions, by the cerebral volume. Accordingly, in normal cases, when we speak of the cranial volume, we are speaking by implication of the _cerebral volume_; and all anthropological questions regarding the volumetric development of the cranium in reality have reference to the brain.

In abnormal cases, on the contrary, it may happen that the bony covering is not a skeletal index of the brain; in fact, pathological cases may occur analogous to those we have already observed in discussing the etiology of cranial malformations, in which the flat bones of the cranial vault undergo a notable thickening, so that as a result the greater volume of the cranium is due to the increased quantity of bony substance, and not of brain tissue, and is very heavy, so that it readily droops over upon the shoulder: _pachycephalic_ cranium.

Another cause for lack of correspondence between the cerebral and the cranial volume may be the abnormal production of cerebro-spinal fluid within the brain: _hydrocephalic_ cranium.

=The Development of the Brain.=--In the earliest period of embryonal life, the brain consists of a single vesicle, the continuation of which forms the spinal marrow: later on, this vesicle divides into three superimposed vesicles which represent respectively the embryonal beginnings of the anterior, middle and posterior brain; continuing their development, the anterior and posterior brains each divide in turn into two other vesicles, so that there result in all five primitive vesicles of the brain, superimposed one upon another (see Fig. 75); the anterior vesicle which is destined to grow enormously, dividing into two parts, right and left, with a longitudinal division, will constitute the cerebral hemispheres; the second vesicle will constitute the optic thalami; the third vesicle, the corpora quadrigemina; the fourth vesicle, the cerebellum, and the fifth vesicle, the medulla oblongata.

When complete development is attained, the cerebral hemispheres completely cover the other parts of the brain, besides which they themselves are covered over with a multiplicity of folds constituting the _convolutions_. If we take a cross-section of the hemispheres, we find that they consist of an outer layer of _gray_ matter formed of nerve cells, and of a central mass of _white_ matter, formed of fibres.

The study of the convolutions is quite important from the anthropological standpoint, because their number is not identical in the different branches of the human race, and also because they differ both in number and in arrangement from the convolutions in the brain of the anthropoid apes. But however interesting they may be, considered as differentiating characteristics, we cannot linger over a study of this kind, which has a purely theoretic importance, and for the present cannot be applied in any practical and direct way to our problems of pedagogic anthropology. It will be sufficient to note rapidly that at the present time the study of the _convolutions_ has received a new impulse through the labours of certain distinguished investigators, among whom we must once more include Dr. Sergio Sergi. Instead of studying the surface convolutions, Dr. Sergi studies the internal folds which are disclosed by separating the lips of the cerebral fissures; and from these he draws deductions which to a large extent correct those made by previous scientists, in regard to the eventual ancestry of the different species, the marks of biological superiority or inferiority, the differences in the brain due to sex, etc.

The surface fissures which divide the cerebral hemispheres into convolutions are shown in the two accompanying figures (Figs. 76 and 77), the first of which shows the outer side of the hemispheres, and the second the inner side.

Of chief importance to us is the arrangement of convolutions and furrows on the outer surface of the hemispheres.

The points to be noted are the following: the two great fissures, Rolando's, running longitudinally, and Silvius's running transversely, which, together with the perpendicular fissure, divide the hemisphere into four lobes: the _frontal_ lobe and the _parietal_ lobe, situated respectively in front and behind Rolando's fissure; the _temporal_ lobe, situated below Silvius's fissure, and lastly, the _occipital_ lobe at the posterior apex of the hemisphere.

In the third frontal convolution are situated Broca's centres, which are believed to be the seat of articulate speech; while along Rolando's fissure, in the ascendant convolutions, is the locality designated by physiologists as the motor centres.

The occipital lobe is the location of the zone of sight; and the temporal lobe, that of hearing.

It is important for us to observe the volume of the brain, and therefore that of the head, in relation to the rest of the body; it is enormous in the embryo; and even at birth and during childhood the head is quite voluminous as compared with the body, as appears from the diagram in Fig. 16, in which a new-born child and an adult man are reduced to the same scale, each retaining his relative bodily proportions. In Fig. 22 a new-born child is shown in two positions: from the front and from behind; the head is very large and the cranial nodules are plainly visible. Figs. 80 and 81 represent the same child at the age of six months and a year and a half; in the first picture the head is still very large as compared with the body, and the forehead protrudes (infantile forehead); in the second, the proportion between head and body has already altered.

A knowledge of the laws governing the growth of the brain is of particular importance in relation to pedagogic anthropology.

Within the last few years anthropologists have established certain principles that are well worthy of notice:

1. The child's head is normal when its _volume_ and _cephalic index_ come within the limits of normality (even if the shape appears abnormal: Simon, Binet, etc.).

2. When the volume of the head is too small it frequently indicates psychic deficiency; when it is too large, even up to the age of twenty years, it indicates a predisposition to precocious mortality (see below).

Very frequently when the size of the head is larger than normal and is not due to pathological causes (rickets, hydrocephaly, etc.), it is associated with an excessive development of the brain, and also with an intellectual precocity. A high percentage of this type die before reaching the age of twenty years; and this fact confirms the popular belief that children who are too intelligent or too good cannot live long.

This indication alone ought to be sufficient to prove the pedagogic importance of the cerebral volume.

The researches made by various authors in regard to the growth of the brain are not rigorously in accord as to the _limits of volume_: but they do agree as to the _rhythm of growth_.

Welcker gives the following figures:

WEIGHT OF THE BRAIN IN GRAMS
(According to WELCKER)

------------------------------
Age | Males | Females
------------+-------+---------
At birth | 400 | 360
Two months | 540 | 510
One year | 900 | 850
Three years | 1,080 | 1,010
Ten years | 1,360 | 1,250

Accordingly, the weight of the brain is doubled before the end of the first year; according to Massini it is very nearly doubled at the end of the first six months:

MASSINI'S FIGURES AS TO THE WEIGHT OF THE BRAIN

--------------------------------------------------
Age |Total weight| Increase
---------------------------+------------+---------
At birth | 352 | 68 }
First month | 420 |211 } 279
From first to third month | 631 |
From third to sixth month | 675 | 44 }
From sixth month to 1 year | 694 | 19 } 63

It follows from these figures that by the end of the sixth month the weight of the brain is already very nearly doubled; but the maximum growth takes place between the ages of one month and three, after which it shows a notable diminution of rate.

But while the weight of the whole body is increased threefold by the end of the first year, that of the brain is very far from being tripled, since the rate of growth is still further diminished during the second six months; in fact even according to Welcker the weight at the end of the first year has little more than doubled.

Accordingly the rhythm of cerebral growth is not identical with that of the increase in weight of the body taken as a whole.

According to Massini, the relation between the cerebral weight and the weight of the body, at the various successive ages, is as follows:

RELATION BETWEEN WEIGHT OF BRAIN AND TOTAL WEIGHT
(According to MASSINI)

-----------------------------------------------------------
Age | Brain | Body | Age | Brain | Body
--------------------+-------+------+---------+-------+-----
At birth | 1 | 8 | 2 years | 1 | 15
First month | 1 | 9 | 3 years | 1 | 14
From first to third | | | | |
month | 1 | 9 | | |
to sixth month | 1 | 10 | | |
to one year | 1 | 12 |25 years | 1 | 40
-----------------------------------------------------------

In other words, the body grows more rapidly than the brain, and consequently, than the head: a fact which results in the different proportions already noted between head and body.

The rhythm of brain growth considered by itself has been set forth in a most noteworthy and accurate fashion by Boyd, based on the study of about two thousand cases; from the figures given by Boyd, I have calculated the amount of increase from period to period, as well as from year to year, the whole result being set forth in the following table:

RHYTHM OF GROWTH OF BRAIN
(_Males_: According to BOYD)

-------------------------------------------------------------------------
|Weight|Difference|Difference| |Proportion
Age | in | for each | for each | Relative|to maximum
|grams | period | year | epoch | reduced
| | | | | to 100
-----------------------+------+----------+----------+---------+----------
At birth | 331| -- | -- | -- | 24.2
From birth to 3 months | 493| +162 | -- | -- | 36.0
From 3 to 6 months | 603| +110 | -- | -- | 44.1
From 6 months to 1 year| 777| +174 | +446 |1st year | 56.8
From 1 to 2 years | 942| +165 | +165 |2d year | 69.0
From 2 to 4 years | 1,097| +155 | +77 | 2d- 4th| 80.4
From 4 to 7 years | 1,140| +43 | +14 | 4th- 7th| 83.4
From 7 to 14 years | 1,302| +162 | +23 | 7th-14th| 95.3
From 14 to 20 years | 1,374| +72 | +12 |14th-20th| 100.5
From 20 to 30 years | 1,357| -- | -- | -- | 99.3
From 30 to 40 years | 1,366| +9 | +0.9 |30th-40th| 99.3
From 40 to 50 years | 1,352| -14 | -1.4 |40th-50th| 98.9
From 50 to 60 years | 1,343| -9 | -0.9 |50th-60th| 98.3
From 60 to 70 years | 1,315| -28 | -2.8 |60th-70th| 96.9
From 70 to 80 years | 1,289| -26 | -2.6 |70th-80th| 95.3
From 80 to 90 years | 1,284| -5 | -0.5 |80th-90th| 94.2
-------------------------------------------------------------------------

In the above table, the first column of figures gives the _mean_ _average weight_ of the brain, obtained by direct observation of individual subjects; while from all the others the rhythm of cerebral growth and involution throughout the successive periods of life may be computed.

We see that the maximum growth takes place in the first years of life, the intensity is greater in the first year than in the second, and greater in the first three months than in those that follow. Already at the end of the first year the brain has surpassed one-half of the maximum weight which the individual is destined to attain in adult life (last column: proportions computed on scale of 100). A notable rate of increase continues up to the age of four, after which it moderates, but receives a new impulse at about the fourteenth year (period of puberty); hence it appears that at this important epoch of life the _brain_ not only shares the general rapid growth of the body, but that by the end of the fourteenth year the brain has _already practically completed its development_; in fact, assuming that 100 represents its complete development, the weight of the brain is already 95.3; and at thirty it will be only 99.3.

By studying the above table we can obtain a clear analysis of these phenomena.

For women, Boyd gives the following figures:

THE GROWTH OF THE BRAIN IN WOMEN
(Figures Given by BOYD)

--------------------------------------------------
| |Proportion to the
Age | Weight | maximum reduced
| | to 100
-----------------------+--------+-----------------
At birth | 283 | 22.8
Three months | 452 | 36.5
From 3 to 6 months | 560 | 45.2
From 6 months to 1 year| 728 | 58.8
From 1 to 2 years | 844 | 68.1
From 2 to 4 years | 991 | 80.8
From 4 to 7 years | 1,136 | 91.7
From 7 to 14 years | 1,155 | 93.3
From 14 to 20 years | 1,244 | 100.4
From 20 to 30 years | 1,238 | 100.0
From 30 to 40 years | 1,218 | 98.3
From 40 to 50 years | 1,213 | 97.9
From 50 to 60 years | 1,221 | 98.2
From 60 to 70 years | 1,207 | 97.4
From 70 to 80 years | 1,167 | 94.2
From 80 to 90 years | 1,125 | 90.8
--------------------------------------------------

The rhythm of growth of the female brain is analogous to that of the male, except for the more precocious attainment of the maximum weight, which corresponds to the more precocious evolution of the female organism.

It should be noted that in the tables above cited the maximum is actually given as occurring at the age of twenty; and that after this period the weight diminishes again, subsequently increasing up to an age that varies according to the sex. But this maximum at the age of twenty must be considered as one of the false results of mean averages; and it must be explained on the ground that after the twentieth year the death rate has eliminated a series of individuals whose heads were abnormally large, and that a majority of the survivors were those whose heads had developed within normal limits.

This fact is further confirmed by Wagner's figures, cited by Broca:

MEAN WEIGHT OF THE BRAIN
(According TO WAGNER)

--------------------------------------
Age | Men | Women
--------------------+--------+--------
Under 10 years | 985 | 1,033
From 11 to 20 years | 1,465 | 1,285
From 21 to 30 years | 1,341 | 1,249
From 31 to 40 years | 1,410 | 1,262
From 41 to 50 years | 1,391 | 1,261
From 51 to 60 years | 1,341 | 1,236
Above 60 years | 1,326 | 1,203

Here again we have a false maximum at twenty, which nature subsequently corrects through mortality.

From such knowledge we obtain certain important rules of hygiene.

The normal brain which exceeds the common limits of volume is not, in an absolute sense, _incompatible_ with life. We need only to call to mind certain men of genius who had the brains of a giant.

Accordingly a brain which exceeds the limits _demands of the_ _individual who possesses it_ that he shall live according to certain special rules of hygiene. Children and young people who are _too intelligent_, _too good_, in other words, children of the elite class demand a special treatment, just as much as any other class of beings that pass beyond the bounds of average normality. Parents and teachers ought to be enlightened in regard to these scientific principles; the growth of individuals who are exceptional in regard to their intelligence and their emotions, should be supervised as though it were something precious and fragile. Such individuals are destined to be more subject than others to _infective_ _maladies_, which frequently prove fatal, developing symptoms of meningitis and cerebral affections. Consequently a hygienic life, _psychic repose_, an avoidance of emotional excitement, moderate physical exercise in farm or garden, a prolonged stay in the open country, might be the salvation of children of this type, who often are over-praised and over-stimulated by friends and relatives, and consequently subjected to continual excitement and _surménage_ to a degree destructive to their health.

=Extreme Individual Variations of the Volume of the Brain.=--In regard to individual variations, the authorities give various figures, from which the following have been selected as most noteworthy for their accuracy of research:

NORMAL EXTREMES OF INDIVIDUAL VARIATIONS IN THE VOLUME
OF THE BRAIN

-----------------------------------------------------------
| Age: from 20 to 60 years| From 60 to 90
Authors |-------------------------+-----------------------
| Maximum | Minimum | Maximum | Minimum
---------+------------+------------+------------+----------
Calori | 1,542 | 1,024 | 1,485 | 1,080
Bischoff | 1,678 | 1,069 | 1,665 | 1,080
| | | |
| _Without distinction of age_:
Broca | Maximum | Minimum
| 1,830 | 1,049
-----------------------------------------------------------

These figures refer to individuals belonging to European races.

_Comparison with the Brains of Apes._--The brain of the great anthropoid apes (Chimpanzee, Orang-utan, Gorilla), whose total weight of body is comparable to that of man, weighs on an average 360 grams, and the greatest weight which it can attain is 420 gr.

_Specific Gravity of the Human Brain._--In normal individuals, the average specific gravity is 1.03; in insane persons it is slightly higher: 1.04.

_The Relation between the Weight of the Brain and the Cranial_ _Capacity: Figures given by Lebon_:

Weight of the brain Cranial capacity in
in grams cubic centimetres

1,450 1,650
1,350 1,550
1,250 1,450
1,150 1,350

_Figures given by Manouvrier_:

Weight of the brain Cranial capacity in
in grams cubic centimetres

1,700 1,949
1,450 1,663
1,250 1,432
1,000 1,147

=Increase in the Volume of the Brain.=--Studies regarding the growth of the head, although not yet complete, have gone sufficiently far to give us some useful ideas. In regard to the volume in a general sense, the _cranium in its growth obeys the cerebral_ _rhythm_.

We shall speak in the section on _Technique_ of the methods of measuring the head: at present it will suffice to point out that the measurements may be made directly upon the cranium, and the _cranial capacity_ calculated directly from the head: and that the _maximum linear measurements_ are sufficient to indicate the volume--such measurements being the three maximum diameters, _longitudinal_, _transverse_, and _vertical_, and the _maximum circumference_. Even the forehead, as an index of the general volume of the brain, is of interest in researches relating to the volumetric growth of the head.

Regarding the growth of the several cranial dimensions, the most accurate and complete knowledge is furnished by Binet's researches among the school-children of Paris (1902).

This author has made special investigations into the _rhythm_ of growth of the cranium and of the face, with special reference to the period of _puberty_. The following are the mean averages obtained by him, relative to the three diameters corresponding to the three maximum dimensions of the head:

MEAN AVERAGES OF CEPHALIC MEASUREMENTS TAKEN UPON
CHILDREN OF DIFFERENT AGES
(BINET: _From the schools of Paris_)

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| Kinder- |Lower primary schools |Upper pri- |Normal
| gartens | |mary schools|schools
|-----------+-----------------------+------------+-------
Measurement | 4 | 5 | 8 | 10 | 12 | 14 | 14 | 16 | 18
|years|years|years|years|years|years|years| years| years
---------------------+-----+-----+-----+-----+-----+-----+-----+------+------
Antero-post. diameter|169.5|173.9|174.7|177.1|181.5|181.5|185.3|188.3 | 190.4
Transverse diameter |140.6|141.7|145 |145.7|147.9|150.1|155.5|152.3 | 156.7
Vertical diameter |118.8|121.6|122 |122.8|127.6|129.7|128.1|131.4 | 130.8
-----------------------------------------------------------------------------

It is evident that these figures contain inaccuracies, especially in regard to the vertical diameter (where the subsequent two-year period gives a smaller measurement than the preceding) due to the fact that the averages were obtained from an insufficient number of subjects or from subjects differing too widely in intelligence (from schools of different grades). For this reason Binet summarises the differences in growth, that is, the increase in relation to the diameters, under broad groups (six year groups, from four to ten years, and from ten to sixteen), in order to determine whether puberty exerts a sensible influence upon the cranial growth. The result is contained in the following table:

INCREASE OF THE THREE MAXIMUM DIAMETERS OF THE HEAD IN
MILLIMETRES FROM FOUR TO EIGHTEEN YEARS OF AGE

---------------------------------------------------------------------------
Age in years: from -- to -- | 4-6; 6-8; 8-10 | 10-12; 12-14; 14-16 | 16-18
----------------------------+----------------+---------------------+-------
Antero-posterior diameter | 5.6; 0.8; 2.4 | 4.4; 1.8; 5 | 2.1
| \-----------/ | \------------/ |
| \/ | \/ |
| 8.8 | 11.2 |
Transverse diameter | 1.1; 3.3; 0.7 | 2.2; 3.9; 0.5 | 4.4
| \-----------/ | \------------/ |
| \/ | \/ |
| 5.1 | 6.6 |
Vertical diameter | 2.8; 0.4; 0.8 | 4.8; 2.3; 2.5 | 0.6
| \-----------/ | \------------/ |
| \/ | \/ |
| 4.0 | 9.6 |
---------------------------------------------------------------------------

From which it appears that there exists, in regard to the head, a puberal acceleration of growth.

These conclusions of Binet are indirectly confirmed by the researches of Vitale Vitali regarding the development of the forehead in school-children; since it is well known that the forehead represents the index of the general growth of the cerebral cranium.

Vitale Vitali based his observations upon school-children and students between the ages of ten and twenty. He not only measured the width of the forehead (_frontal diameter_; see _Technique_), but also measured its height, obtaining the percentage of its relation to the width (frontal index).

These are his figures:

FRONTAL INDEX AND DIAMETER ACCORDING TO AGE

(VITALE VITALI: RESEARCHES AMONG SCHOLARS AND STUDENTS
FROM 10 TO 20 YEARS OLD)

------------------------------------------
Age | Frontal | Frontal | Amount of
| index | diameter | increase
---------+----------+----------+----------
11 years | 73.05 | 107.5 | --
12 years | 74.11 | 112.0 | 4.5
13 years | 74.14 | 112.5 | 0.5
14 years | 74.80 | 114.4 | 1.9
15 years | 75.67 | 116.8 | 2.4
16 years | 77.24 | 120.1 | 3.3
17 years | 77.02 | 120.6 | 0.5
18 years | 77.36 | 121.5 | 0.9
19 years | 77.60 | 122.8 | 1.3
20 years | 77.15 | 122.1 | 0.7
------------------------------------------

Accordingly, between the years of fourteen and sixteen there is a puberal acceleration of growth, accompanied by an elevation of the forehead (high frontal index).

Vitali gives, as extreme limits of the frontal index, 68 and 83.

But in order to give a better illustration of the author's figures, his own words may be quoted: "It appears from our observations that the forehead begins to develop in notable proportions during the fourteenth year, and that the development of the frontal region as compared with the parietal region continues to augment up to the sixteenth year; after this it still increases, but only by a few millimetres, until the end of the sixteenth year. The cephalic development is completed between the sixteenth and eighteenth years. This observed fact is of great importance in relation to the development of the intellect."

The most complete figures at the present time on the growth of the brain, are those of Quétélet, which follow its development from birth until the fortieth year. They are summarised in the following table:

INCREASE IN THE CIRCUMFERENCE OF THE BRAIN AND IN ITS
THREE MAXIMUM DIAMETERS
(ACCORDING TO QUÉTÉLET)

--------------------------------------------------------------------------
| | Maximum diameters
Age |Circumference |------------------------------------------------
|in millimetres | Antero-post. | Transverse | Vertical
---------+---------------+---------------+---------------+----------------
| Men | Women | Men | Women | Men | Women | Men | Women
At birth | 335 | 335 | 120 | 120 | 100 | 100 | 80 | 80
1 year | 440 | 439 | 158 | 157 | 127 | 126 | 105 | 105
2 years | 471 | 469 | 168 | 167 | 135 | 134 | 113 | 113
3 years | 486 | 483 | 171 | 170 | 137 | 136 | 117 | 115
4 years | 496 | 493 | 174 | 173 | 138 | 137 | 119 | 116
5 years | 503 | 500 | 176 | 175 | 139 | 138 | 120 | 117
6 years | 508 | 505 | 178 | 177 | 140 | 139 | 121 | 117
7 years | 513 | 509 | 179 | 178 | 142 | 140 | 122 | 118
8 years | 519 | 512 | 180 | 179 | 143 | 141 | 123 | 118
9 years | 523 | 515 | 181 | 180 | 144 | 141 | 124 | 119
10 years | 527 | 517 | 182 | 180 | 145 | 142 | 125 | 119
11 years | 531 | 518 | 183 | 181 | 146 | 142 | 126 | 120
12 years | 535 | 519 | 184 | 181 | 147 | 143 | 127 | 121
13 years | 539 | 520 | 185 | 182 | 147 | 143 | 128 | 122
14 years | 543 | 521 | 186 | 182 | 148 | 144 | 129 | 123
15 years | 547 | 523 | 186 | 183 | 149 | 144 | 130 | 124
16 years | 551 | 525 | 187 | 183 | 150 | 145 | 130 | 125
17 years | 555 | 528 | 188 | 184 | 151 | 145 | 130 | 125
18 years | 561 | 531 | 189 | 184 | 152 | 146 | 131 | 126
19 years | 563 | 533 | 190 | 185 | 153 | 146 | 131 | 126
20 years | 564 | 535 | 191 | 185 | 153 | 147 | 131 | 126
25 years | 564 | 537 | 191 | 186 | 153 | 147 | 131 | 127
30 years | 564 | 538 | 191 | 186 | 153 | 147 | 131 | 127
40 years | 564 | 538 | 191 | 186 | 153 | 147 | 131 | 127
-------------------------------------------------------------------------

It appears from the foregoing table that after the twenty-fifth year the growth of the cranium practically ceases in all directions. In regard to the rhythm of growth, the problem is rendered clearer by the following table, which gives the annual increase:

ANNUAL INCREASE IN THE MAXIMUM CRANIAL MEASUREMENTS
IN MALES
(FROM FIGURES GIVEN BY QUÉTÉLET)

---------------------------------------------------------
Age| Circumference | Antero-post. | Transverse | Vertical
| | diameter | diameter | diameter
---+---------------+--------------+------------+---------
1 | 105 | 38 | 27 | 25
2 | 31 | 10 | 8 | 8
3 | 15 | 3 | 2 | 4
4 | 10 | 3 | 1 | 2
5 | 7 | 2 | 2 | 1
6 | 5 | 2 | 1 | 1
7 | 5 | 1 | 1 | 1
8 | 6 | 1 | 1 | 1
9 | 4 | 1 | 1 | 1
10 | 4 | 1 | 1 | 1
11 | 4 | 1 | 1 | 1
12 | 4 | 1 | 1 | 1
13 | 4 | 1 | 1 | 1
14 | 4 | 1 | 1 | 1
15 | 4 | 1 | 1 | 1
16 | 4 | 1 | 1 | 1
17 | 4 | 1 | 1 | 1
18 | 4 | 1 | 1 | 1
19 | 4 | 1 | 1 | 1
20 | 1 | 1 | 1 | 1
---------------------------------------------------------

It appears from the above table that the total growth of the cranium takes place to a notable extent during the early years of life; as regards the diameters, the longitudinal diameter grows faster during the first few months than the transverse; but after the first year, the two maximum diameters which determine the cephalic index increase in very nearly the same proportion (constancy of the cephalic index throughout life). The vertical diameter on the contrary undergoes a relatively much greater increase than the two others, since, although much shorter than the transverse, it nevertheless overtakes and surpasses it in its absolute annual increase.

This corresponds to the fact that the first two diameters are indexes of growth relative to the base of the cranium, while the vertical diameter is the index of expansion of the cranial vault, which more directly follows the growth of the brain and elevates the forehead as it pushes upward.

Quétélet's figures, however, fail to show in the rhythm of growth that puberal acceleration which has been observed to take place in the growth of the brain. This contradicts the researches of Vitali and also those of Binet.

Similar studies have been made a number of times during the last few years, especially in America, but with English tables of measurement, and with little uniformity in the results obtained by the different investigators.

Among the most recent and most complete figures should be cited those of Bonnifay[38] in which however the measurement of the vertical diameter is lacking, or in other words the third element needed, in conjunction with the dimensions of length and breadth, to give the volumetric factors.

CRANIAL MEASUREMENTS AT DIFFERENT AGES
(According to BONNIFAY)

--------------------------------------------------------------------------
| Absolute figures | Amount of Increase
|--------------------------+--------------------------
Age from -- to -- |Circum-| Antero- | Trans- |Circum-| Antero- | Trans-
|ference|posterior| verse |ference|posterior| verse
| | diameter|diameter| | diameter|diameter
--------------------+-------+---------+--------+-------+---------+--------
Birth to 15 days | 343.9 | 116.3 | 93.4 | -- | -- | --
15 days to 2 months| 368.7 | 126.3 | 99.1 | 24.8 | 10.0 | 5.7
3 months to 4 months| 388.8 | 132.7 | 106.0 | 20.1 | 6.4 | 6.9
6 months to 1 year | 429.8 | 145.4 | 118.2 | 41.0 | 12.7 | 12.2
1 year to 2 years| 459.7 | 154.3 | 129.3 | 29.9 | 8.9 | 11.1
2 years to 3 years| 473.5 | 161.9 | 133.3 | 13.8 | 7.6 | 4.0
3 years to 4 years| 487.4 | 166.2 | 136.3 | 13.9 | 4.3 | 3.0
4 years to 5 years| 495.7 | 169.9 | 138.3 | 8.3 | 3.7 | 2.0
5 years to 6 years| 497.8 | 171.9 | 140.4 | 2.1 | 2.0 | 2.1
6 years to 7 years| 504.4 | 172.8 | 141.1 | 6.6 | 0.9 | 0.7
7 years to 8 years| 511.6 | 175.2 | 143.7 | 7.2 | 2.4 | 2.6
8 years to 9 years| 514.1 | 176.1 | 144.3 | 2.5 | 0.9 | 0.6
9 years to 10 years| 514.7 | 176.4 | 144.2 | 0.6 | 0.3 | 0.9
10 years to 11 years| 519.8 | 177.1 | 146.6 | 5.1 | 0.7 | 2.3
11 years to 12 years| 521.1 | 177.5 | 145.7 | 1.3 | 0.4 | 0.1
12 years to 13 years| 529.7 | 180.1 | 147.8 | 8.6 | 2.6 | 1.2
13 years to 14 years| 533.1 | 178.1 | 148.5 | 3.4 | -- | 0.7
14 years to 17 years| 548.8 | 182.4 | 152.2 | 15.7 | 2.3 | 3.7
22 years to 27 years| 549.1 | 186.6 | 153.2 | 0.3 | 4.2 | 1.0
--------------------------------------------------------------------------

Among the linear measurements of the cranium, the one which serves to give the most exact index of volume is the _maximum_ _circumference_.

This index, nevertheless, is not a perfect one, in the same sense that the _stature_, for instance, is a perfect index in respect to the body, because in the case of the cranium another element enters in: the form. The cranial circumference of an extremely brachycephalic cranium (almost circular) may contain a larger surface (and consequently include a larger volume), than a maximum circumference of the same identical measure, which belongs to an extremely dolichocephalic cranium (approaching the shape of an elongated ellipse). This may be easily understood if we imagine a loop of thread laid out in the form of a circle: if we pull it from two opposite sides, the enclosed area diminishes until it finally disappears as the two halves of the thread close together, while the length of the thread itself remains unaltered.

Nevertheless, the maximum circumference still remains the linear index best adapted to represent the _volume_; indeed, the authorities take its proportional relation to the stature as representing the reciprocal degree of development between head and body at the different successive ages.

Here are the figures which Daffner gives in this connection:

DEVELOPMENT OF THE STATURE AND OF THE CEPHALIC PERIMETER
FROM BIRTH TO THE AGE OF ELEVEN YEARS

------------------------------------------------------------------------
| Males Females
--------+---------------------------------------------------------------
Number | |Stature| Cranial | Number | |Stature| Cranial
of | Age | in |perimeter,| of | Age | in |perimeter
subjects| | cms. | cms. |subjects| | cms. | cms.
--------+--------+-------+----------+--------+--------+-------+---------
65 |At birth| 51.17 | 34.58 | 65 |At birth| 50.27 | 34.23
11 | 1.55 | 74.18 | 46.74 | 10 | 1.39 | 77.20 | 46.45
30 | 2.43 | 85.32 | 48.03 | 30 | 2.45 | 83.48 | 47.23
53 | 3.34 | 91.88 | 49.20 | 49 | 3.43 | 89.97 | 47.73
112 | 4.43 | 96.64 | 49.55 | 81 | 4.50 | 96.07 | 48.37
244 | 5.42 |103.21 | 50.21 | 208 | 5.40 |100.61 | 48.76
234 | 6.41 |106.49 | 50.73 | 179 | 6.37 |104.92 | 49.87
30 | 7.30 |114.47 | 51.66 | 25 | 7.36 |117.36 | 50.38
28 | 8.38 |112.10 | 51.97 | 24 | 8.41 |121.58 | 50.72
27 | 9.40 |128.41 | 52.38 | 30 | 9.40 |126.76 | 51.10
21 | 10.34 |129.12 | 52.24 | 28 | 10.40 |130.00 | 51.08
20 | 11.42 |135.84 | 52.50 | 31 | 11.46 |137.04 | 51.42
------------------------------------------------------------------------

DEVELOPMENT OF THE STATURE AND OF THE CEPHALIC PERIMETER
BETWEEN THE YEARS OF 13 AND 22

------------------------------------------------------------
Number of subjects | Age | Stature in | Cephalic perimeter
| | centimetres| in centimetres
-------------------+-------+------------+-------------------
13 | 13.39 | 147.92 | 52.83
24 | 14.50 | 149.21 | 53.53
20 | 15.38 | 163.55 | 54.34
41 | 16.43 | 162.53 | 53.34
35 | 17.36 | 167.93 | 55.89
26 | 18.35 | 171.65 | 54.91
15 | 19.40 | 172.97 | 55.48
6 | 20.05 | 173.97 | 56.50
342 | 21.02 | 168.08 | 55.37
171 | 22.22 | 168.08 | 55.62
------------------------------------------------------------

One very important research made by Daffner is in reference to the maximums and minimums that are normal for each successive age. This is extremely useful for the purpose of diagnosing the _morphological normality in relation to the age_. He naturally bases his figures upon subjects studied by him personally, who altogether form an aggregate number of 2,230, and are not always sufficiently numerous when distributed according to their ages. Nevertheless, in the great majority of groups, especially those including the younger children, the number of subjects is sufficient and even superabundant.

At all events, Daffner's researches may serve as a valuable guide in the researches that lay the foundation for diagnosis; and every future investigator will find it an easier task, under such guidance, to make his own contribution to it and to correct those inaccuracies which (for certain epochs) are to be attributed to an insufficient number of subjects.

Daffner distinguishes, for each year, a _maximum_ and a _minimum_ both for the stature and for the cephalic perimeter; but since the person having the maximum stature does not always have the maximum cephalic perimeter, and _vice versa_, the author indicates, in connection with the maximum and minimum figures, the other of the two measurements which, as a matter of fact, corresponds to them in each given case.

INDIVIDUAL VARIATIONS

MAXIMUMS AND MINIMUMS OF STATURE AND OF CRANIAL
CIRCUMFERENCE

----------------------------------------------------------------------
| Measurements |Maximum (M.) |Measurements occurring
| S.--Stature |and |in combination with
Age | Cc.--Cranial |minimum (m.) in |the M. or m.
| circumference |millimetres |measurements
-----------+-----------------+----------------+-----------------------
| Males from birth to the age of eleven years
|
At birth |Cranial circumf. {M. = 372 |(S. = 625).
________ | {m. = 326 |(S. = 500).
|Stature {M. = 550 |(Cc. = 369, 365, 354).
| {m. = 480 |(Cc. = 343, 341, 337).
-----------+----------------------------------+-----------------------
1 year |Cranial circumf. {M. = 491 |
______ | {m. = 456 |
|Stature {M. = 805 |(Cc. = 491).
| {m. = 680 |(Cc. = 456).
-----------+----------------------------------+-----------------------
2 years |Cranial circumf. {M. = 506 |(S. = 855).
_______ | {m. = 462 |(S. = 800).
|Stature {M. = 920 |(Cc. = 496).
| {m. = 785 |(Cc. = 467).
-----------+----------------------------------+-----------------------
3 years |Cranial circumf. {M. = 521 |
_______ | {m. = 462 |(S. = 915).
|Stature {M. = 995 |(Cc. = 521, 501).
| {m. = 795 |(Cc. = 472).
-----------+----------------------------------+-----------------------
4 years |Cranial circumf. {M. = 530 |(S. = 1035).
------- | {m. = 465 |(S. = 900).
|Stature {M. = 1090 |(Cc. = 510).
| {m. = 835 |(Cc. = 499, 481).
-----------+-------------------------------------+------------------------
5 years |Cranial circumf. {M. = 527 |(S. = 1070).
------- | {m. = 481 |(S. = 930).
|Stature {M. = 1173 |(Cc. = 519).
| {m. = 920 |(Cc. = 495).
--------------------------------------------------------------------------
6 years |Cranial circumf. {M. = 532 |(S. = 1090).
----- | {m. = 481 |(S. = 1045).
|Stature {M. = 1163 |(Cc. = 517).
| {m. = 950 |(Cc. = 495).
-----------+-------------------------------------+------------------------
7 years |Cranial circumf. {M. = 541 |(S. = 1232).
_____ | {m. = 502 |(S. = 1156, 1223).
|Stature {M. = 1276 |(Cc. = 527).
| {m. = 1092 |(Cc. = 514).
-----------+-------------------------------------+------------------------
8 years |Cranial circumf. {M. = 542 |(S. = 1207, 1292).
_____ | {m. = 496 |(S. = 1158).
|Stature {M. = 1375 |(Cc. = 537).
| {m. = 1099 |(Cc. = 497).
-----------+-------------------------------------+------------------------
9 years |Cranial circumf. {M. = 548 |(S. = 1333).
_____ | {m. = 507 |(S. = 1250).
|Stature {M. = 1383 |(Cc. = 546).
| {m. = 1185 |(Cc. = 522).
-----------+-------------------------------------+------------------------
10 years |Cranial circumf. {M. = 553 |(S. = 1303).
______ | {m. = 497 |(S. = 1270).
|Stature {M. = 1372 |(Cc. = 538).
| {m. = 1218 |(Cc. = 534).
-----------+-------------------------------------+------------------------
11 years |Cranial circumf. {M. = 543 |(S. = 1350).
_____ | {m. = 505 |(S. = 1307).
|Stature {M. = 1466 |(Cc. = 542).
| {m. = 1300 |(Cc. = 513).

Note. ----- indicates that the number of subjects is abundant.
_____ indicates that the number of subjects is sufficient.
..... indicates that the number of subjects is scarce.

FEMALES FROM BIRTH TO THE AGE OF ELEVEN YEARS