Compare the connective tissue of bone with that of fat, and let the pupils account for the difference in thickness. Lead them to see that connective tissue can be dissolved in hot water, and in this way may be extracted from the mineral part of bone. The housekeeper may do this herself, or she may buy it already extracted, as gelatine. 5. Composition of muscle: (1) Connective tissue (2) Red part, made up of microscopic tubes holding a red juice. The juice contains: (_a_) Water (_b_) Red colour (_c_) Flavour (_d_) Muscle albumen--a protein substance similar to egg-white (_e_) Mineral matter. [Illustration: Muscle fibres highly magnified Bundle of fibres. Tubes of one fibre. Proper carving of fibres--across the grain.] It should be made clear that the walls of such tiny tubes can never be thick enough to be tough. Attention should be called to the real cause of toughness--the thick connective tissue. NOTE.--Very small pieces of meat will serve for specimens. Tough meat is better, because it shows the connective tissue more plainly. When the muscle is being examined, it should be carefully scraped with a knife, until a layer of connective tissue is laid bare. The red part that is scraped off should be explained, and a drawing should be made to illustrate it. Minced lean beef should he soaked in a little cold water for at least twenty minutes, to extract the muscle juice for examination. The juice should be strained through a cheesecloth and poured into a glass. It shows nothing but water and a red colour. In order to find the other substances, pour part of the juice into a small saucepan and heat it gradually until it boils gently. The red colour will disappear, and the albumen which is dissolved in the juice will coagulate and become plainly visible. The pupils will recall that egg-white was affected in the same way by heat, and may be told that this coagulated substance is similar to egg-white, and is called muscle albumen. The odour given off by heating suggests that the flavour is also in the muscle juice, hence the importance of conserving this juice in the cooking process. Strain the boiled juice to get rid of the coagulated albumen and then examine the liquid that is left. Its colour plainly denotes mineral matter in solution. LESSON II 6. Meat experiments: If time permit, the following experiments may be taken. The facts which these experiments prove may, however, be developed in a much shorter time by questioning: (1) Cut lean meat into small pieces, cover them with cold water and let them stand. Note the colour of the water. (2) Cover a piece of lean meat with boiling water and let it stand. Note the colour of the water. (3) Sprinkle a piece of meat with salt. What happens?