Puberty, the period of youth characterized by the acquirement of functional power in the reproductive apparatus of the sexes; its activity, however, cannot be called into exercise until the growth of the individual is completed, on penalty of premature and permanent exhaustion of the vital powers, and the development of any latent disposition to disease. That puberty is not the period of completed growth is shown by the increase in stature after its attainment, the subsequent complete ossification and consolidation of the extremities of the spinous and transverse processes of the vertebrae, and the consolidation of the pelvic, sacral, and coccygeal vertebrae, sternal pieces, and epiphyses of the ribs, scapula, clavicle, and bones of the extremities. In the human male puberty is established between the 14th and 16th years; besides the increased sexual and muscular development, the beard makes its appearance, the larynx enlarges, giving a lower, harsher, and stronger tone to the voice, and the thoughts, desires, and actions have a more manly character.

In the female this period is arrived at between the 13th and 16th years in temperate climates, and somewhat earlier in the tropics and in the midst of the luxury and excitements of city life; there is a similar development in the reproductive system, usually coincident with the appearance of the catamenia and mammary enlargement, and a deposition of fat over the whole surface of the body. In the male there is at this time no special tendency to disease, nor in the healthy female; but, as a consequence of the defective physical training of most female youth, disorders of the menstrual function are very apt to occur, with numerous functional, nervous, and even organic complications; in persons of naturally weak constitutions, of both sexes, and in those enfeebled by premature exercise of the mental, physical, or generative powers, the tuberculous diathesis is frequently developed soon after puberty.