The suprarenal capsules or adrenals are ductless glands largest in the fetus, where they exceed the kidneys them- selves, and become steadily smaller at least to forty, according * See Burke. Scatological Rites.
' See, e. g., Sprengel Geschichte der Arzneikunde, B. ii passim and B. iii, p.
PARTS AND ORGANS DURING ADOLESCENCE "7 to Lorey, Bischof, and Schwann. Some now think they aid in removing the toxic products produced by the muscles dur- ing exercise.
The liver was thought to continue to grow well on into old age, but later determinations indicate that it grows rela- tively very slowly after fifteen, and from that age on to senes- cence has a weight progressively less compared to that of the body. The following is Miihlmann's table for males: Agb.
Abs.
Rel.
Its circulatory mechanism, so inadequate for oxidization and elimination, may account for the great amount of unoxi- dized material it contains and why it deposits fat and atro- phies so easily. It receives only about the same amount of arterial blood as the kidneys, although it weighs about six times as much in the adult, and less than the milt, although it is a little over nine times heavier.
Ritter's analysis of the bile at different ages gives the following table: Age.
Solid residuum.
Matter.
Natrium.
Organic.
Inorganic.
Glycochol acid.
Taurochol acid.
14 21 23 25 III. 7 II. 4 The salivary glands also increase in size and function. Tt has often been noted that their activity is augmented with ii8 THE PSYCHOLOGY OF ADOLESCENCE intensity of the sexual life. In the almost epidemic outburst of venery, which travelers describe, as the arctic spring ad- vances after the long winter night, not only is the liver stim- ulated so that constipation and jaundice cease and menstrua- tion becomes more profuse and frequent, sometimes with hemorrhage from the mouth and nose, but saliva flows with great and offensive exuberance. When temperature rises, respiration becomes more frequent, bleeding is easier in this purest of all airs, when spring seems full of premature joy, and distils the wine of action, and when everything quivers with the wild passion of life after its long depressing winter.^ The jaws increase in size and power, and there is a new propensity to bite, chew, smoke, and to taste various stimulants which act as ptyal- agogues. Questionnaire returns also show an increased dis- position now to spit with various artistic refinements and even competitions as to distance, accuracy, method, and amount, while idiots become offensive by drooling. The change in the sensitiveness and quality of tastes and appetites later discussed is also connected with adolescent hypersalivation. These and certain emotional phenomena also indicate a wide irradiation of glandular sympathy at this age.
The milt or pancreas continues to grow till old age. Miihlmann has compiled from seven measurements the follow- ing tables for males: Age.
Abs.
76 86 70 Rel.
^ Cook. Some Physical Effects of Arctic Cold, Darkness, and Light. York Medical Record, July 12, 1897.
New PARTS AND ORGANS DURING ADOLESCENCE 119 The pancreas, like the spleen, develops from the wall of the intestinal tract; like that organ, it is under the control of special nerves, but it secretes alkaline as the spleen does acid products. Its maximal secretion is during the first hour after eating, and its minimal three or four hours later. The pubes- cent growth of both these glands is far greater than that of the body as a whole, so that some, so far unknown, significance for this age seems suggested.
The spleen grows yet more rapidly during adolescence. Roberts's table for males is as follows: Age. Spleen, oz.
The spleen is one of the most mysterious organs of the body. Unlike any other, it has its own local arrangement for maintaining circulation. After every meal it increases greatly in size, then contracts synchronously with diges- tive periods, and probably has a shorter rhythm of varo-dila- tion. It can be removed without serious danger. Probably it aids in the process of producing red blood-corpuscles, and possibly destroys old ones. Vierordt thinks it continues to grow till at least the forty-seventh year. It need hardly be said that the spleen has no more relation with the psychic quality which suggested its name and was once thought to be located in it than sweetbread has with sweetheart.
The sebaceous glands over the surface of the skin, which secrete in the new-born child the vernix caseosa, corresponding to the lanolin of sheep's wool, the oily matter of birds' feathers, cerumen or ear-wax, preputial smegma, etc., are more active at puberty. Their secretions about the hair-follicles increase, some think, with changed quality. They are often obstructed so that sebum accumulates, causing pimples or comedones. In the axillae or armpits especially, these glands reveal their morphological afHnity to those of the mammae, and the fre- quent dryness and irritability of the hands and sometimes of the entire dermal surface, often noted in states of nervous weakness after coition, show their functional sympathy with 120 THE PSYCHOLOGY OF ADOLESCENCE testes and ovaries. Their odor is quite sui generis, and since Haller's description of this as due to the more volatile parts of this sperm diffused through the flesh, a popular concep- tion widely diffused has ascribed genital odors to thern in gen- eral, centering, however, in their peculiar secretions on the organs of sex, which are greatly modified by function and disease. Jager's vague speculations on his discovery of the soul as a smell rested for its meager basis of fact largely upon exploitations of the facts connected with the action of these glands. Pornographic literature abounds in suggestions in this field; lewd people's dread of water, certain arts of breed- ers to secure cross-fertilization between species that nor- mally do not mate at all, perfumes used to make birds sing, and a distinct odor ascribed to puberty in savage races by anthropologists may also be recalled here. Many of our returns specify moisture, clamminess, or, more rarely, dryness of the hand in adolescents, along with heat and coldness, when also the face very often becomes covered with indications of abnormality in these secretions. Modifications of dermal sensi- tiveness and itching, the passion for being stroked, patted, and caressed, and other erogenic phenomena connected with the sense of touch, to say nothing of laboratory tests of hepatic sensibility at this age thought to be connected with these secre- tions, intimate how deep is the rapport between them and the new functions of sex.
A man loses about as much sweat as he does urine, and these two sources of outflow are complemental. Each have nervous centers in the medullary region which are adjacent to each other. It must be remembered, however, that while urine is a true secretion, sweat is also a heat regulator. At puberty the amount of water imbibed and given out in both these ways is increased. Sweating is easier and more pro- fuse, no doubt partly from the increased relative weakness that attends rapid growth. Many returns state that the odor of perspiration from underwear at this age is both stronger and different than heretofore. Whether these modifications are due to growth of the glands or modifications in the nervous control to which they are subject is unknown. Travelers and anthropologists have thought that characteristic national odors so marked that negroes, Chinese, and even Irish, Germans, and PARTS AND ORGANS DURING ADOLESCENCE others can be distinguished by the aroma of their sleeping- rooms, underwear, etc., and which are far more marked at puberty, are partly sudoriferous.
Pigmentation, which Laycock ascribes to imperfect oxi- dation, undergoes more or less modification. Sometimes the hair slightly changes its hue, in such cases more com- monly growing a shade darker; the eyes are often thought to change color, light eyes sometimes grow lighter and dark eyes darker; a few have thought they detected slight color modifications in the skin, although these may have been accounted for by changes of circulation which affected only complexion. Certain it is that the sex organs, the nipples, and aureola become distinctly darker. In mixed races, espe- cially in mulattoes, testimony would indicate frequent modi- fications both ways.
As to whether the lachrymal glands share the general aug- mentation of the secretory function, we find no evidence save only the repeated statement that weeping is more frequent in girls for a few years after the dawn of puberty than before.
The following is Puech's table showing the average dimensions of the ovaries at different ages: Right.
Left.
Length.
Height.
Thickness.
Length.
Height.
Thickness.
New-born...6-II yrs 9 15 18 10 24 25 35 14 I3-I Miihlmann, from a few determinations, gives their weight as follows: Weight of both Ovaries.
He has also weighed the testes at different ages, with the fpllgwi.ng results:, THE PSYCHOLOGY OF ADOLESCENCE Weight of Testes.
Some think that in contrast with the ovaries, which after the cHmacteric are reduced greatly, the testes continue to grow. That they do not share the general post-climacteric involu- tion which comes later in men is not yet sufficiently estab- lished.
On the other hand, two secretory organs rapidly decline in size, one relatively and the other absolutely, during ado- lescence. The mysterious thymus gland, which is large at birth, is reduced one-half and sometimes to a vestige before puberty, and often vanishes between twenty-five and thirty- five. It has, however, no known connection with this age save perhaps through its relation with the thyroid gland higher up in the lower part of the neck. The latter has lately come to be of great and growing interest, through its relation with the blood and nutrition, which are known to be very important, although not yet well understood. At birth its weight is yJtt, in maturity about Ywuiy* ^^^^ ^^ ^^^ body. After, but not before puberty, it can be extirpated without very great danger. It is larger in women than in men, swells consid- erably at the first and somewhat after all successive men- struations, also after the first coitus even in men. To measure the neck is a wide-spread test of virginity and also ceremo- nially of nubility, among rude and savage people. It enlarges also during pregnancy and lactation, so that its sympathy with the uterus is close. Exophthalmic goiter and myxedema, which involve extreme facial and other expressions resembling fear, seem to be based on thyroid troubles, and both diseases often occur during the later stages of puberty. After thyroidectomy the pituitary body often hypertrophies, and the suprarenal bodies are affected. Its connections with sex- PARTS AND ORGANS DURING ADOLESCENCE 123 ual functions, especially in the female, and its close and neces- sary relation with nutrition, which have in recent years given rise to a vast body of literature, are both accentuated by the fact that at the dawn of senescence this gland is peculiarly liable to degenerative disease.
Fat seems to decrease at puberty in vigorous boys. If it preexisted, it is often then used up as if it were reserve material accumulated for the sake of growth. Boys are often described in our returns as lean, spidery, scrawny, cadaver- ous, as having lost their plumpness of limb and feature and their good looks. This is partly due to the increased relative prominence of the joints and the points for muscular attach- ment. Not only are the curves and angles sharper, but the limbs are relatively longer as compared with the trunk than they were in childhood, and this adds to the general dishar- mony of proportions. A chapter might be written on the morphological ugliness of the boy.
While girls also often grow thin, the increase of cellular tissue in the mammary and the growth of the pelvic region in its horizontal expansion are in a sense complementary. The hips, thighs, limbs, shoulders, and arms round out into contours more or less beautiful, and with curves always pre- dominating over angles, while not only on the bony promi- nences, but over, between, and in the fibers of the great mus- cles themselves, adipose and other intracellular tissue pads all parts and members into more or less rounded and graceful outlines.
The thickness of the subcutaneous adipose tissue shows, of all parts of the body, most irregular development. Kotel- mann found it to increase up to nineteen years almost exactly as height increases and along with muscle growth. In relation to weight, it maintains a pretty constant relation of from three to nine per cent.
The temperature of the body is partly due to nutrition and partly to causes not yet explained. A large part of the total energy of life is consumed in producing bodily heat. Loss of heat varies considerably with the relation of surface to mass of body, which in the adult is only about three-eighths what it is at birth, although the determinations of the effects of sex and age upon calorification are not yet in complete accord.
124 THE PSYCHOLOGY OF ADOLESCENCE The child at birth has a slightly higher temperature than the uterus of its mother. After a considerable fall it begins at about the second hour after birth to rise, and thereafter through childhood is on the average about 37.5"^ C, or about 0.3° more than the adult, nearly half a degree warmer awake than asleep. In general, however, temperature taken in rectum, mouth, and armpits rises a little between the ages of five and nine. Some think puberty is marked by a distinct rise, which has been estimated as high as 0.5° F. It then sinks slightly from the fifteenth to the twenty-fifth year, when ado- lescence is well established, and falls to a minimum at about the fiftieth. It is highest a few days before menstruation, and may vary normally 0.5° or even 1° F. Although sexual dififerences of temperature are not yet well established, present indications point to a slightly higher temperature in males, who also present greater individual variations. Children also vary much more within the limits of normal change than do adults. Other things being equal, the smaller the body the greater the changes caused by outer temperature.
Harmonious Growth. — There is no one fixed standard of proportion of parts or of beauty either in art or in anthropome- try. Even Erismann's law that " During the development of puberty, the squares of the weights in different ages are related to each other as the fifth power of the length " is only an approximation. Man the measurer, who has in the past used his forearm (cubit, ell), his foot, his girth (yard from gyrdon), his length (fathom), his thumb (pouce), nail, hand, as standards and metric units, and has selected some dimension in many art canons — length of face, foot, palm, middle fin- ger, ear, nose, etc. — as a modulus (so many times which gave the true dimensions of other parts), has always been and still is more autotypic than he knows, reproducing in his rep- resentation of the human form the type of his own race. Some of these schemes of proportion have been elaborately and even mystically wrought out in detail, treated mathe- matically, and applied even to architecture. The special part to which all the rest sustained occult relation has sometimes been thought to be able in some way to furnish a key to unlock the secrets of our being. Anthropometry, however, shows that; a true type is something very different from all PARTS AND ORGANS DURING ADOLESCENCE 1 25 these normal figures. The modern head, e. g., is larger than the Greek canons permitted, and Fock lately proved that the only length of the upper arm that corresponded to the Apollo Belvedere was the Ethiopian type, thus suggesting an Egyptian origin of the Greek norm.^ True beauty in the human form, the type of the divine, can not be absolute or uniform. Apollo does not inspire young men now to esthetic ideals of art, while the type or mean form of the fifty percentile line repre- sented, e. g., in Sargent's casts, at the Chicago Exposition, of the average male and female collegian is positively repellant. Young men especially desire to develop individuality by de- parting more or less widely from standard forms without be- coming distinctly disproportionate. Perfect symmetry of body, then, either in form or function, is rare and more or less asymmetry is the rule.
The bilateral halves of the body differ in size, strength, rapidity, and in temperature. The blood-vessels are of dif- ferent size, the eyes are unlike in acuteness and in mobility, the two hemispheres of the brain, the number of fibers in the pyram- idal decussation are unlike, while liability to disease is some- times greater in one half of the body than in the other. It is impossible to make symmetrical movements with both hands, the preferred hand always making the greater excursion. Pages would be needed to simply enumerate the asymmetries in form and function of the right and left half of the body that have been specially studied.^ Bolton ^ found that children were symmetrical until adolescence, and until early pubescent years when the shoulders or head tip slightly, the spine curves, the two sides of the face grow unlike, eyes, hips, feet, legs differ- entiate, the relative ambidexterity declines, and the dis- position to lop and stoop in sitting and standing, to sleep on one side in preference to the other, and in general to spe- cialize the two halves of the body, is augmented. The Am- * See Robert Fletcher. Human Proportion in Art and Anthropometry. Cam- bridge, 1885.
Also W. S. Hall. Changes in the Proportions of the Human Body during the Period of Growth. Journal of the Anthropological Institute, 1895.
^ See Bilateral Asymmetry of Function. G. Stanley Hall and E. W. Hartwell. Mind, xxxiii.
^ Proceedings of the Colorado Teachers' Association, Session 1896.
126 THE PSYCHOLOGY OF ADOLESCENCE herst measurements show that the right thigh, calf, instep, upper arm, forearm, breadth of shoulders and elbow tip are at this time greater than the left. These differences are greater in men than in women, and the differentiation of the bilateral structure and functions is accelerated at adolescence.
Dr. Hrdlicka^ found among i,ooo children that the max- imal number of abnormalities occurred at the age of from eight to nine, and then distinctly decreased, puberty tending to diminish them. Massive gums common in children are very rare after this age, and the nose, which may be low or broad before, then assumes ordinary proportions. The au- thor says: ''All habit abnormalities tend to increase in pro- portion as we advance from early childhood. From my observations on adults and adolescents outside of the institu- tion, I think that after the age of fifteen or sixteen these abnormalities tend again to diminish, a certain proportion of them being spontaneously corrected." Genital irregularities, particularly adhesion of the prepuce, diminish rapidly after puberty.
Smedley's Chicago Report (No. 2) shows that the aver- age number of growth abnormalities seen in pupils below grade is strikingly more than in those at or above grade, whether this difference be sought among children of differ- ent standing in the same school or whether the comparison be between the averages of higher grade and those of schools for backward children.
Dr. Francis Warner suggests that the same conditions that caused ill-proportioned development of the body may also have caused the tendency to ill balance of nerve-centers, and that even the converse of this may possibly be true. Overaction of the frontal muscles, e. g., may go with cranial defect, and the action of cause and effect may work either way or indeed both ways. Dr. Warner thinks that many of his new nerve signs or symptoms go with disproportioned growth. If this relation of past structure to present func- tion be estabhshed, environment and education should have power to control to some extent the proportionality of growth, so that even reversions may be temporary. Girls, * Special Report of Anthropological Investigation on i,ooo White and Colored Children of the New York Juvenile Asylum, pp. 117-172.
PARTS AND ORGANS DURING ADOLESCENCE 127 although less often abnormal than boys, seem more influ- enced by environment if they are defective. Disordered nerve states appear to go with defective bodily structure. It is a disadvantage, again, to be tall, broad, and heavy if the lungs, heart, or stomach are not proportioned to the increased size, which imposes a strain upon them, and they then become more liable to collapse. If the reproductive parts and all the complex apparatus connected with them, which are from their very intricacy so peculiarly liable to arrest by fatigue, excitement, low diet, etc., are subnormal, race deterioration is certain no matter how complete in other respects individual development may be.
From these data we see that sexual maturity involves changed relations of parts which for a time lessens their coor- dination and unity. Moreover, if we include rudimentary or- gans in our survey, we see that many parts are growing less and vanishing, especially in childhood. Some grow on into old age, and are even then at least relatively young. Structures vary in size more or less independently of each other, and the warring equilibrium of proportionate growth is more or less disturbed. Some parts are arrested or decline while others rapidly increase. Some vary directly with each other, some inversely. Such changes are far more numerous and more rapid in the infant, and still more so in the growth of the embryo; but in these respects they are analogous in their nature, although later growths are less prede- termined, rapid, or transforming. At birth respiration, phonation, and a new mode of alimentation spring into function. In teething and weaning, new forms and qual- ities of food involve changes in salivation and many reflex disturbances. So puberty is not unlike a new birth, when the lines of development take new directions. The range of individuality in nearly all respects — size, strength, motion, mental ability, etc. — is greatly increased, extremes are wider apart, and average variations ampler, as seen in wider distributions among the percentile grades. This means increased plasticity and docility, so that powers of acquisition are increased and deepened. There is much reason to be- lieve that the influence of the environment in producing acquired traits transmissible by heredity is greatest now, 128 THE PSYCHOLOGY OF ADOLESCENCE although perhaps the influence of experience upon the germ- plasm may be greatest a Httle later. Changes of ethnic de- velopment best occur now, and the point of departure for higher and more evolved forms is adolescence and not adult- hood, just as upward steps in the development of the phylon have not been from the terminal types of earlier periods, but have started from stages farther back.
So, too, if the soul grows with every part of the body, its development is not continuous, uniform, or propor- tionate, but with successive nodes, the earlier stages ever a little more strange and alien to the newer, like dimly remem- bered past lives to a transmigrationist. The fact that coordi- nations are a little loosened, and that parts can vary more inde- pendently of each other and are freer from the control of the whole, make this the age of modification and plasticity more than the few years that precede or than all those that follow.
It is the age of reconstruction, when new determinants come to the front and also the point of departure for new lines of development. It is the age, too, when, if ever, previous tend- encies to abnormality may be overcome both by nature and by treatment. The law of nascent periods, or the age curve of growth of each organ or faculty, is one of the first desider- ata of genetic psychology; how to apply it, by what means and to what degree to stimulate each part in its stage of most and least rapid growth, and how to apportion training of mind and body between developing the powers that excel to a degree of specialized culture that corresponds to their hered- itary possibilities, or educating the weakest parts and powers in order to improve proportion and symmetry, is one of the chief problems of individual pedagogy.
CHAPTER III GROWTH OF MOTOR POWER AND FUNCTION Educational value of special study in this field illustrated — Importance of muscle culture for the development of mind and morals, relations to sex, the lift and pull — Growth of biceps and " putting " power, pressing power of hands and knees, leg strength, grip and grasping, maximal rate of tapping, growth in accuracy, precision and inhibition, right- and left-hand power, fatigue, second breath, reaction time, reproduction of time intervals, fundamental and acces- sory power, mobility of children, automatic movements, their meaning and repression, control, motor efficiency, monotony, motor degeneration of modern man, tendencies to motor revival. I. Industrial training, monotechnic and trade schools and their results. II. Manual training, its defects, criticism of sloyd, arts and crafts movement, motor methods illustrated by telegraphy and drawing. III. Gymnastics: (a) ideal of doing everything possible with the body as a machine, the movement of Jahn; (d) ideal of volitional control; (c) ideal of economy in movement; (</) ideal of symmetry; calamity of rival systems, effects of exercise on strength, athletic records. IV. Play and sport — A new theory corrective of Groos, ancient Greece, the charm of play traced to the plylon, the doll, number of plays and games, team play records, rhythm, dancing, plays of conflict, the duel, student honors, military training, play and sex, cold baths and swimming, playgrounds, regimentation of plays and gam«s and professionalism, play and work.