The more highly organized tissues found in the animal are composed of five elements, as muscle, brain, blood; these are Oxygen, Carbon, Hydrogen, Nitrogen, and sulphur. Albumen, for example, exists in most of the tissues of the body, but especially in the nervous tissue, lymph, chyle, blood, etc. Fibrine is found most abundantly in the blood and the more perfect portions of the lymph and chyle. Gelatinous substances are contained in the cellular or fibro-cellular tissues in all parts of the body, as tendons, ligaments, cartilages, bone, skin, mucous membranes, etc. Chondrine is obtained from cartilages, etc. The general chemical composition of these substances is as follows: Albumen. Fibrine. Gelatine. Chondrine. Carbon 52.5 52.7 50.40 49.97 Hydrogen 7.0 6.9 6.64 6.63 Nitrogen 15.5 15.4 18.34 14.44 Oxygen 22.0 23.5 28.58 Sulphur 1.6 1.2 24.36 } 0.38 (Inorganic } elements.) } Phosphorus 0.4 0.3 ------ ------ ------ ------ 100.00 100.00 100.00 100.00 It will be observed that in the composition of these tissues, more than half of their constituent elements is Carbon. There is but a very small quantity of Hydrogen. The most abundant inorganic substance in the body is water, which is composed of Oxygen one and Hydrogen two (OH2). More than two-thirds of the body is made up of water. The body is composed of various structures. Of the chief tissues of the human body, the weight is as follows: The skeleton 15.9 per cent. The muscles 41.8  ,,   Thoracic Viscera (lungs, heart, etc.) 1.7  ,,   Abdominal Viscera (liver, etc.) 7.2  ,,   Fat 18.2  ,,   Skin 6.9  ,,   Brain 1.9  ,,   Let us examine, briefly, each of these. The skeleton.--The skeleton, or solid framework of the body, is mainly formed of bones, but is completed in some parts by the addition of cartilages. The bones are bound together by means of ligaments, and are so disposed as to support the softer parts, protect delicate organs, and give attachment to the muscles by which the different movements are executed. There are two hundred and four bones in the body: