The earliest sign of approaching puberty is a deposit of fat in the loose cellular tissue under the skin. This gives roundness to the form, and grace to the movements. According to a distinguished naturalist (Buffon), it is first observable by a slight swelling of the groins. Thence it extends over the whole body. The breasts especially receive additions, and develope to form the perfect bust. Parts of the body previously free from hair become covered with a soft growth, and that which covers the head acquires more vigor and gloss, usually becoming one or two shades darker. The eyes brighten, and acquire unwonted significance. These windows of the soul betray to the close observer the novel emotions which are arising in the mind within. The voice, too, shares in the transformation. The piping, slender articulation of the child gives way to the rich, melodious, soft voice of woman--the sweetest music man ever hears. To the student of humanity, to the observant physician, nothing is more symbolical of the whole nature than the voice. Would you witness a proof of its power? Watch how a person born blind unerringly discriminates the character of those he meets by this alone. Beyond all external modifications, we find others, which indicate how profound is the alteration now taking place. The internal organs of the body assume new functions and new powers. The taste for food changes, hinting that the system has demands hitherto unknown. Those organs we have adverted to, called the ovaries, increase in size, as also does the uterus. The very framework of the structure does not escape. The bones increase in weight, and those around the hips expand, and give the female her distinctive form, upon the perfection of which her life and that of her children depend. MENTAL CHANGES. Such are the changes which strike the eye. But there are others which are not less significant, and which demand far more urgently our watchful heed. New thoughts, strange desires, are invading the soul. A novel relation is assumed to the world. It is vague, misunderstood, but disturbing all the same. The once light-hearted girl inclines to reveries; she seeks solitude; her mother surprises her in causeless tears; her teacher discovers an unwonted inattention to her studies, a less retentive memory, a disinclination to mental labor; her father misses her accustomed playfulness; he, perhaps, is annoyed by her listlessness and inertia. What does it all mean? What is the matter with the girl?