PUBERTY. MENSTRUATION. 951 



PUBERTY. 



The time at which man begins to be sexually mature is designated the 

 age of puberty. In females this occurs between the thirteenth and the 

 fifteenth year, in males between the fourteenth and the sixteenth year. 

 In hot climates girls are often sexually mature as early as the eighth 

 year. Between the forty-fifth and the fiftieth year, with the cessation of 

 menstruation, the reproductive period terminates in the female (climac- 

 teric, involution); while in the male the production of spermatozoa is 

 observed even to most advanced age. From the time of puberty sexual 

 desire is awakened and the matured germinal material is expelled. All 

 of the internal and external sexual organs, together with their accessory 

 structures, undergo increase in size and become more vascular; the pelvis 

 of the female acquires a characteristic shape. The evolution of the 

 breasts is described on p. 418. The pubic and axillary hairs, in the male 

 the beard, make their appearance in conjunction with increased sebace- 

 ous secretion. 



The period of puberty is attended with alterations in many other organs: 

 the larynx of the boy increases in size considerably in a sagittal direction, and the 

 vocal bands become longer and thicker, so that the voice becomes at least one octave 

 deeper (and therefore "breaks"). In the female the larynx becomes longer 

 in its entirety, and the range of the voice is also increased. The vital capacity in- 

 creases considerably in correspondence with the enlargement of the thorax. The en- 

 tire figure and face acquire the contour characteristic of the sex, and the mental 

 tendencies also receive a characteristic stamp at puberty. The vegetative develop- 

 ment with relation to the individual is ended and the stream of growth in organic 

 strength now passes in the direction of new production or procreation. 



MENSTRUATION. 



At regular intervals of from 27 J to 28 days (solar month) there 

 occurs in the sexually mature woman rupture of one or several mature 

 Graafian follicles, with the coincident appearance of a bloody discharge 

 from the external genitalia. This phenomenon is designated men- 

 struation (menses, catamenia, courses, periods, monthly purification). 

 Most women menstruate during the first quarter of the moon, 

 only a few at the time of the new or full moon. In mammals 

 the analogous process is termed heat; especially in carnivora, 

 horses, and cows there is a bloody discharge from the genitalia, and 

 the apes of the old world have a well marked menstrual bleeding. 



The onset of menstruation is usually preceded by signs indicative of increased 

 flow of blood to the internal genitalia, such as drawing pains in the sacral regions 

 and the loins, as well as in the region of the uterus and the ovaries, which are 

 sensitive to pressure, fatigue in the legs, flushes, alternate heat and cold, and 

 even slight elevation of temperature in the external integument. In addition 

 there may be sluggishness of gastric digestion, abnormalities in the evacuation 

 of feces and of urine and secretion of sweat. It is noteworthy that during men- 

 struation the decomposition of the nitrogenous elements of the body in the meta- 

 bolic process is diminished. 



The menstrual discharge is at first mucoid, then bloody, and it lasts three or 

 four days (rarely from one day to two weeks) . The blood has the characteristics 

 of venous blood and, if admixed witbTa copious alkaline genital secretion, it ex- 

 hibits a lessened tendency to coagulation, which may, however, take place in 

 clumps if the bleeding be active. The amount of blood discharged approximates 

 between 100 and 200 grams. After cessation of the bleeding itself there is a 

 moderate discharge of mucus. Subsequently sexual desire is generally increased. 



