In the OS calcis, the junction of the epiphyses and bone occurs at about fifteen or sixteen. The tarsal bones and even the metatarsals and phalanges show distinct progress in ossi- fication about and soon after puberty. The instep is a trifle more arched, the sole some think distinctly broader, and the great toe seems to lose power of opposition and to become confirmed in its structure as well as in its function of sup- porting the body and springing. Jager thinks certain changes in the form and position of the human foot are acquired and not inherited. At birth the foot is oblique, so that only the outer edge touches the floor; it is drawn upward from its right- angular position, so that the heel would first touch, and is very flat. When first used, it must be placed squarely down over all its surface, and the anterior metatarsi are also pressed against the basis of support. If thus every irritation of the periosteum, on which lateral growth is assumed to depend, and of the car- tilaginous disks between the diaphysis and the epiphyses, on which longitudinal growth is known to depend, increases the production of bone substance, then the progressive changes in the form and position of the human foot must, he thinks.
PARTS AND ORGANS DURING ADOLESCENCE &9 be explained as the results of experience and not of congen- ital influence.
After puberty two small epiphyses appear both in the head and tubercle of the ribs and join the main bone by fhe twenty-fifth year. The sternum ossifies progressively, begin- ning with the complete union of the third and fourth members of the body, leaving the cartilage below the manubrium to be ossified soon after puberty. The carcinoid process joins the body of the scapula, and epiphyses appear from the four- teenth to the sixteenth years, coalesce, and join the spine six or seven years later. If we regard the scapula, clavicle, and ribs as the thoracic girdle, it is phylogenetically sinking, owing, perhaps, to the upright position. Cervical ribs are now only found in man in abnormal cases and the upper rib is beginning to degenerate, but the decay at the lower part of the thorax is more rapid than at the upper part. Even the eleventh and twelfth ribs are rudimentary, and there are abundant traces of former supernumerary ribs below, where in the horizontal position they were needed to support the viscera. Thus as the thorax has flattened from front to back and broad- ened laterally as man became erect, a change also marked from infancy to maturity, the adolescent chest growth is mainly lateral, while its length becomes relatively less.
Marro's measurement of chest circumference shows little increase from ten to twelve years, then a development reaching its maximum rate at fifteen, but continuing to nineteen. For the total period from eleven to nineteen years the augmenta- tion was from 0.62 to 0.76 meters. Kotelmann concluded -that the circumference of the thorax, which in adults is one-half the length of the body, does not attain that relation until about nineteen, and grows most rapidly at puberty. Hrd- licka found it relatively deepest from front to back in infancy, and that it grew broad and flat with age up to the early teens. Porter found chest girths nearly equal from thirteen on for two or three years, but that boys excelled girls at all ages in chest expansion, girth of chest being usually about equal to sitting height.
The pelvic girdle, as if also in response to a downward tendency of the center of gravity, is, as it were, slowly creep- ing up the spine. At any rate, the trunk was once longer 70 THE PSYCHOLOGY OF ADOLESCENCE and the upper sacral vertebrae, the incorporation of which with the hip-bone is later than with the lower vertebr.-e, have left us now a trifle uncertain whether man has twenty-five or twenty-six presacral vertebrae. This relative approximation of the upper and lower bony girdle is easier because both are de- veloped later than the skeleton of the limbs.^ The pelvic region, especially in girls, undergoes impor- tant pubertal changes. The iliac arches broaden, the Y car- tilage, separating the three parts of the hip-bone, begins to ossify from several centers about the age of puberty, and the epiphyses about the crest of the ilium unite with the main bone at from twenty-three to twenty-five years of age. Com- plementary and intercalary bony points develop and join, espe- cially the newly discovered cotyloid bone of Albinus between the pubis and the ilion, which join at eighteen. There is en- largement in like manner in the region of the symph)^sis pubis, and sometimes so great as to noticeably rotate the neck of the femur and toes outward in girls. The transverse diameter of the pelvis, which before is often less than the antero-posterior, now becomes greater and the inclination of the pelvis is decreased. These changes give firmer support to the large iliac and gluteal muscles, better sustain the viscera, and make balance easier, especially laterally, and may cause noticeable modification in posture and carriage. The five sacral and four coccygeal bones unite at from eight to ten years, but are fully fused into one at fifteen or eighteen. The sacrum and coccyx are often not completely joined at twenty-five, and the mobility of the latter, particularly its lower members, which is maintained very late in women, plays an important role in confinement. The female pelvis is broader horizontally relatively to that of the male. The dimensions of the iliac fossae are less in the female, the dis- tance of the OS pubis is greater, and it has an inclination to the horizon of at least five degrees more than that of the male.
The development of the female pelvis is one of the most exact expressions of puberty, coinciding in time and follow- ing completely the growth and needs of the organs it con- tains. The parallel between the development of the two is as close as that of the sexual organs themselves and the * Wiedersheim. Structure of Man, 1895, p. 32 et seq.
PARTS AND ORGANS DURING ADOLESCENCE 71 breasts. All the many points of differentiation from the male pelvis seem to be increasing in civilized lands, and pelvic dimensions increase with the degree of cephalization at birth, in which racial differences are so well pronounced. Sexual dimorphism is nowhere so marked in the pelvic region as in man. Complete pelvic development is rarely attained till well into the twenties for women, and is of profound importance for normal maternity. In this respect, the sexes seem to be growing unlike in many communities instead of alike, and from the mechanism of this part alone we see how every kind of physical training involving its activity should be modified for women during and after pubescence.^ Sargent^ found that the girth of hips from thirteen to sixteen is one and three- fourth inches larger in girls than in boys, and that they were more than two inches larger in the girth of thighs. From seven to twelve Landsberger found that the greatest breadth of hips in- creased from 18.2 to 21.9 centimeters.
(c) Growth of the Head. — The development of the face is a long, slow process, and to fully trace it we must begin as low down as the lamprey, where the skull appears. The fantas- tic faces of fishes and even ophidians, which often suggest so many kinds of ugliness to us, have very little expression. The head moves but little, independently, and the movements of jaws and eyes constitute the only expression. This is true even in birds. As we ascend the animal series, we see the snout slowly forming and developing to a nose, at first em- bryonic; the lips acquire increasing and independent mobil- ity; the superciliary ridges, crests, brows, and eyebrows de- velop; the cheek-pouches, jaws, and, last of all, the nose and chin appear. In many animals, ear movements seem to be those most expressive of inner states of mind; in others, the tail; in still others, secretions — excretory, salivary, etc. The circulatory system becomes very expressive, and blushing, paling, and changes of heart rate respond to every flit- ting change in the psyche. Again, respiration is a deHcate register, as is the voice. Pupils, patella tension, delicate * Some of these later differences are very briefly summed up in Bierent's La Puberte, i8g6. See chiefly, however, the standard texts on human anatomy, in which the above data are found.
' The Physical Development of Women. Scribner's Magazine, i88g.
72 THE PSYCHOLOGY OF ADOLESCENCE changes in the timbre of the voice, in the depth and form of respiration, in the movement of the eye and all its adjacent parts, the posture of the head, the permanent expression and the range and kind of mobiHty of nostril, forehead, and mouth, constitute a very comprehensive repertory of ex- pression, the development of which is an interesting chapter, the richness of which the superficial current treatises on expression in no wise suggest, but conceal.
Perhaps no part of the body has been so much measured and discussed as the skull. Its philogenetic origin and rela- tion to the vertebra is a problem the solution of which Goethe suggested, and it seems to have perennial interest. Cranial capacity is measured in various ways. Torok ^ enumerates 535 skull measurements. Benedict ^ insists that his many score of cathetometric determinations shall be made " with crystallographic exactness," and Rieger ^ sees in studies of skull dimensions a power of distinguishing ethnic stocks almost comparable to the value ascribed by phrenologists to its curves as exponents of mental and moral traits. While there is some reason to surmise that the long-headed races tend to excel the round- or broad-headed races in the competition seen in civilized^ and particularly in urban life (Schlitz concluded that dark and long-headed pupils stood highest, although he found a mixture of long and broad heads superior to pure types), there are so few problems in this field yet solved that the very great number of cranio- metric measurements sometimes insisted on seem at present little more than an affectation.
The length of the face from the middle of the chin to the beginning of the hair Landsberger found to increase between six and thirteen years from 14.7 to 16.5 centimeters. Quetelet found it to increase between six and maturity from 16 to 18.6 centimeters, and to grow most rapidly during puberty. This dimension, therefore, increases more rapidly during school age than any other head measurement. While the face grows, the upper arch of the head remains almost stable. Porter • Ueber einen universalen Kraniometer. Leipzig, 1888.
• Kraniometrie und Kephalometrie.
• Ueber die Beziehungen des Schadellehre zu Physiologic, Psychol., u. Ethnolo- gie.
PARTS AND ORGANS DURING ADOLESCENCE 73 found that the height of face from the hair Hne to the point of the chin in boys, whose superiority was greatest at six, decHning at eleven or twelve, underwent marked augmenta- tion at thirteen, was increased still more from fourteen to fifteen, and was also marked from fifteen to sixteen; and that in girls there was a slight increase in the rate of this growth from twelve to fourteen, when till fifteen they equaled or exceeded boys, only to be surpassed by them in the next two years. He found that the superiority of boys decreased from six to thirteen, when girls, having undergone augmentation, almost equaled them for a time, only to be excelled still more by them after fourteen, the girls' development in this re- spect having nearly ceased at sixteen, when boys were still increasing rapidly. The distance from the root of the nose to the point of the chin in boys was distinctly augmented from fourteen to fifteen, while in girls this acceleration was from ten to thirteen or fourteen. In width of face, Porter found that boys' superiority over girls declined from thirteen to sixteen, when there was closest approximation, girls' faces growing broad rapidly from fourteen to fifteen, boys' too, showing distinct pubertal broadening. West found that in width of face boys excelled girls, but were almost equaled by them at twelve, from which age to twenty-one they increased steadily, except for a slight drop at nineteen, at a faster rate than girls, the latter reaching their maximum at eighteen.
Head form is relatively uninfluenced by climate and food, and is one of the clearest of all permanent, hereditary dififer- ences. The best of the head measurements is perhaps the ratio between length and breadth, above eiehty being usu- ally classed as brachycephalic or broad-headed, and below seventy-five being classed as dolichocephalic or long-headed. Ripley ^ concludes that the basal population of Europe in the stone age was composed of long heads, the Eskimos being a relict of the old Cromasfnan stock. Round heads came in from Asia, slowly driving the long heads upland and producing the vast diversity in small space that characterizes the western part of the Old World. Since then nationality * Popular Science Monthly, Feb., 1897, et seq.
74 THE PSYCHOLOGY OF ADOLESCENCE and language have no longer been founded on race, the more relatively permanent mold of true and really pure types was broken, and the mixture caused a ferment which under the name of social and political progress tends toward progressive mediocrity. He concludes that America, be- ing still further mixed and standing betwen the Asiatic breadth of skull and Western length, should persist in the serene impartiality of mongrels, be terrified at no conclu- sion, etc.
Beginning, then, at the vertex, and passing down, we note that there is a gradual increase in the breadth of the skull in both sexes; in girls at least to the eighteenth year, while in boys this development does not seem to be com- plete at twenty-one. This increase is most rapid in boys from fourteen to eighteen, and from about twelve to fifteen in girls. Growth in length of skull from the glabella to the farthest occipital point is greater not only absolutely but relatively, and the pubertal increment is more marked, being greatest from thirteen to fifteen in boys, but continuing at least till twentv, and being slower but more evenly distributed from twelve to eighteen in girls. In these measurements, but most in length, boys exceed girls at all ages; but in all, girls ^ain on, and most nearly approximate boys from ten to thir- teen, and in all, the adolescent increment is distinct but not jsrreat.^ From twelve to nineteen the average distance between the eyes increases from about fifty-two to sixty-two milli- meters.
The diploe and sinuses of some of the bones of the skull are often found growing as late as, and even after puberty. The basi-occipitnl may be joined to the basi-sphenoidal bone by cartilage as late as the twentieth year, when ossification takes place and completes the union in about two years. The air-cells in the temporal bone are not developed till near puberty, and the stylohyoidal process grows with sudden rapidity at puberty, but only joins late in life. At this age, too, the spongy bones which appear at birth join the body of * For these head and face measurements, see G. M. West, Anthropometrische Untersuchungen tiber die Schulkinder in Worcester, Mass., Arch. f. Anthropol., PARTS AND ORGANS DURING ADOLESCENCE 75 the sphenoid. The laminae of the vomer, too, are completely- united with it only at puberty.^ The greatest skull diameter from front to back, according to Quetelet, increases from six to maturity from 17.8 to 19. i centimeters; according to Liharzik, from 17.5 to 21 centi- meters; according to Landsberger, from 16.5 to 17.5 centi- meters at the age of thirteen, when his measurements end. Landsberger holds that the growth of the skull is independent of that of body length and follows laws peculiar to itself. The greatest diameter of the skull from seven to thirteen he found to increase only from 14.6 to 14.7 centimeters, or almost nothing during school age.
The sagittal diameter of the head from the vertex to the middle of the chin, often called height of head, increases from thirteen to sixteen, and in girls is but one-fifth of an inch below that in boys. According to Landsberger, whose figures are slightly higher than those of Quetelet and less than those of Liharzik, it is from 20.7 to 21.7 centimeters.
Sargent found that the mean girth of the head in girls from thirteen to sixteen is but one-fifth of an inch below that in boys.
In length of head. West found boys always superior to girls, but their relative increase was greatest in this respect from eighteen to twenty. In width of head, he found boys to always excel, but to gain upon girls almost steadily from eighteen to twenty-one. Porter found that from fourteen to sixteen there was a marked augmentation in the increase of the length of head in boys; that in girls a similar augmentation began at twelve, and was still in force at sixteen. He found that while boys were superior to girls in length of head at all ages, they were much more so from six to eleven, and that from that age to fifteen girls gained almost steadily upon boys; and that almost the same was true for width of head, only the differences and gains were less marked.
In apes and lower races of men the sutures of the skull unite first in the frontal, then in the parietal, and last in the occipital region, while in civilized man this order is reversed.
^ See Quain, Elements of Anatomy, 9th ed., vol. i, p. 68 et seq.\ also Henle. Handbuch der Knochenlehre, passim.
76 THE PSYCHOLOGY OF ADOLESCENCE Whether this is atavistic or developmental is uncertain. Wie- dersheim thinks that an original independence of ossification centers inherited from lower ancestors may be sometimes retained in the interest of the progressive development of the anterior lobes. Venn's ^ measurements indicate a '* small but decided " increase in head measurements after nineteen in ail students, but this gain is distinctly more in honor than in poll men. Galton ^ found that 258 higher honor English university students had distinctly larger skulls than poll men, in the ratio of 241 to 230.5. But while, according to his computation, the brain of the former increased only three per cent during their college course, that of the poll men increased six per cent. In all cases the head grew after the age of nine- teen. Honor men thus seemed more precocious. Measure- ments do not yet tell us in what part of the skull the later stages of growth are greatest, but by long-continued individual methods, starting from fixed points, this problem does not seem inaccessible. While the relation of the volume of the brain to the cranial capacity varies greatly, and may be twenty per cent less, it would seem a reasonable inference that in grow- ing periods the correspondence is closer and that, as we know the brain to be erethic, pressure from within may be one cause of cranial growth late as well as early in the devel- opment period.
Dr. Warner ^ found that cranial abnormalities, including asymmetry, and also skulls too large or too small, were the most important defects in development. They were not only most numerous, but had the widest correlation with low nutri- tion, nervousness, ordosis, epicanthus, bad balance of head, overcorrugation or overmobility of frontal muscles, and even defects of speech and form of ear.
In what we may conceive as the long developmental strug- gle for existence between the cranial and the facial parts of the skull, the latter would prevail till massive jaws, teeth, and muscles at the entrance of the alimentary canal were overcom- • Cambridge Anthropology, by J. Venn. Journal of the Anthropological Insti- tute, November, 1888.
• Head Growths in Students of University of Cambridge, by F. Galton. Ibid.
• An Inquiry as to the Physical and Mental Condition of School Children. Brit. Med. Jour., March 12 and 19, 1892.
PARTS AND ORGANS DURING ADOLESCENCE 77 pensated in value for survival, by brain power.^ Between eleven and twenty-five four pairs of permanent teeth are ac- quired in the lower jaw. Welcker's table of second dentition is as follows: Month of Appearance.
Name of tooth.
Year of change.
6-8 (under jaw first) First molar tooth.
Inner incisors.
Outer Front premolars.
Eye-teeth.
Back premolars.
Second molar teeth.
Third molar teeth.
7 8 9 10 Daffner ^ concludes that the permanent incisors begin to appear at about six years and nine months of age; that the per- manent eye-teeth and buccal teeth appear between eleven and twelve; that the permanent molars are cut early in the fourteenth year; and that the wisdom teeth appear on the average at about the age of twenty-one years and six months, although this age varies four or five years in different indi- viduals. In general, these teeth appear first on the lower jaw. The deciduous teeth are more primitive in type, and the molars are less useful in warfare, but suggest a change of food habits, and involve greater length of jaw to make room for them and greater strength of muscle. Hence pubertal increase of the lower jaw, which is often specified in our returns, may perhaps be assumed. Increased prominence of the chin, breadth of lower jaw, propensity to chew, to bite hard things, or to perform feats of strength with the teeth and jaws, the frequency with which clenching the teeth is mentioned in our anger returns, which shows a great pubertal development of irascibility, teaches how clearly jaw ten- sion, once a chief factor in battles, is still associated with pug- nacity. This, too, is a theme inviting further research.
Our questionnaire returns also show that it is a very con- mon impression that the lower jaw grows in size during pu- * The Structure of Man an Index to his Past History, by G. R. Wiedersheim, ' Das Wachstum des Menschen. Leipzig, 1897. See also Vierordt. Physiolo- gic des Kindesalters.
7S THE PSYCHOLOGY OF ADOLESCENCE bescent years, most specifying that the chin becomes more prominent, others that it widens at the outer angle, grows deep, strong, and more firmly set. This change, I think, has been pronounced in boys under my observation, and has given the face an aspect of strength and character. It would be natural to expect that the growing width of the face in the molar region would involve increased width in the lower jaw, where the inferior ends of the same muscles are attached. No adequate measurements, however, have yet been published upon this point, although one careful mem- oir ^ shows that the lower jaw in man is heavier between twenty and forty-five than it is later, and that it is always heavier in man than in woman, both absolutely and rela- tively to the weight of the skull. Further research is also needed on this point. It may be here added that Dr. Schlitz,^ in studying 1,413 children between twelve and fourteen in Heilbronn to determine race types, found that all measure- ments involving the chin formation were defective because of its imperfect development. The facial index, too, he thought unserviceable, because the face was not yet com- pletely grown in length.
The nasion, or depression on the level of the eyes be- tween the root of the nose and the beginning of the glabella above, is often said to fill out during puberty in a way to straighten the line joining nose and forehead. This is a thing so frequently specified by intelligent parents in our ques- tionnaire returns that it deserves attention. Dr. F. Boaz has made this region an object of study by taking many drawings, using flexible strips of lead, plaster, etc., with Worcester school children.
That the nose itself grows is generally believed by those making returns, increase in length being most often speci- fied, prominence next, and breadth least often.
Some think that the upper jaw comes forward in the region of the alveolar point, but more think that together with the upper lip it grows in vertical length. Some state that the * Gurriesi e Masetti. Influenza del sesso e dell' eti sur peso del cranio el della mandibola. Revis. Sperimen. di Frenatria, 1895.
' Correspondenz-Blatt fttr Anthropologie, September, 1899.
PARTS AND ORGANS DURING ADOLESCENCE 79 coronal suture now hardens; others that the vertical depth of the skull in the bregma region increases; others that the occipi- tal point grows prominent or they think they first detect bilateral asymmetries, that the eyes come more to the front as if their sockets were more parallel as they were growing farther apart; that the palate grows more or less arched, etc. Such data indicate a wide range of individual variation, and the need of many further measurements. Their value is, of course, chiefly suggestive till confirmed by a large number of meas- urements.
Another change often specified in our returns is a marked increase in the volume of the neck, seen in its circumference and especially in the region of the opisthion. The growth in the circumference of the neck between six and twelve years increases from 24.9 to 27.9 centimeters. Sargent found the neck of girls from thirteen to sixteen about two-fifths of an inch smaller than that of boys. The popular impression of relation between fulness in the upper part of the neck and lower posterior skull, involving the occipital bone and the region of the atlas, on the one hand, and sex on the other, has found expression in many ways.^ In Brittany and Algeria, two ends of a thread are held between the teeth and the loop is drawn tight over the back of the neck. If this loop can be made to pass over the head, the girl is declared fit to marry and the boy must pay taxes, bear arms, etc. Popular vagaries like those of Dr. Damm, a Ger- man therapeutist, who assumes that each nation has a normal life of one thousand years, and that progressive slenderness in the nape of the neck, which increases with ethnic age, is the best index of how far the senescence of a race, nation, family, or individual has proceeded, reflect the same vulgar notion.