Thus, the first essential for the healthy condition of the blood, and thence of the body, is its nourishment. The second, is its purification. Now, the blood is not only the nourishing, but it is also the warming medium of the body. Each moment of our lives, chemical changes and interchanges are going on between the atoms, throughout every portion of our frames: those which have become unfit for the purposes of the living, healthy body, are replaced by fresh ones, by fresh nourishment, brought by the blood in its never-ceasing current of circulation. At the moment the change takes place, heat is given out--the natural warmth of the living being. But the fresh atoms of nourishment having displaced the old ones, the latter necessarily pass into the blood, and as necessarily render it impure, altering its qualities, and converting it from a bright red, life and vigor-supporting agent, into a dark purple fluid, not only unfit to sustain life, but unfit also either to impart energy or proper nourishment to the frame, unless it be perfectly purified by the agencies provided for this purpose. These agencies are principally four, viz., the lungs, the skin, the liver, the kidneys. The first is directly connected with the subject of pure air; the second, with pure air, light, and personal cleanliness; the two last, with food; and all with the last condition of physical health, the blood circulation or distribution. THE TRIALS OF A NEEDLEWOMAN.[9] BY T. S. ARTHUR. (Continued from page 440.) CHAPTER X. WITHOUT venturing the remotest allusion to her parting with her lover, Miss Ballantine commenced her narrative by saying-- "When I left New York with my father, for New Orleans, no voyage could have promised fairer. Mild, sunny weather, with good breezes and a noble ship, that scarcely seemed to feel the deep swell of the ocean, bore us pleasantly on towards the desired port. But, when only five days out, an awful calamity befel us. One night I was awakened from sleep by a terrific crash; and in a little while the startling cry of 'the ship's on fire!' thrilled upon my ear, and sent an icy shudder to my heart. I arose from my berth, and put on my clothes hastily. By this time my father had come, dreadfully agitated, into the cabin; and while his own lips quivered, and his own voice trembled, he endeavored to quiet my fears, by telling me that there was no danger; that the ship had been struck with lightning; but that the fire occasioned thereby would readily be put out.