Fats are derived from the animal and vegetable kingdom; they are rich in carbon and hydrogen, but poor in oxygen. Emulsified fats are present in cream, nuts and the yolks of eggs. Oleins are mainly found in oils obtained from fruits, nuts and vegetables. Butter contains mainly palmitin. Suet, from beef and mutton, consists of stearin and palmitin. Lecithin is found in yolks of eggs and in some nuts; it is a highly complex compound, and a food for the brain and nerve substance. Suet and mutton fat contain much stearin, and are harder to digest by some people than other fats. However, the digestibility of a food depends much upon the individual requirements, and a little self study will soon convince each what forms of fat are best suited to his needs. As a rule, people of large bone structures require a greater amount of fat in their food than those not so constructed. Fats are changed into fatty acids and glycerine by the secretion of the bile and pancreatic juice, and in combination with the intestinal juices form soluble soaps. In acute diseases fats should be taken only in the form of butter, milk, or cream, in limited quantities. Fatty foods are beneficial for children suffering with scrofula or rickets, and in all chronic, wasting diseases. People who do much indoor work, or those who are not able to digest a sufficient amount of protein or cereals, require more fats. The latter can be made easily digestible if rightly combined and prepared in the form of soups, warm sauces, boiled custards and mayonnaise dressing. In this way the fat globules are equally divided in the food and can be better emulsified than if eaten in the solid form, or in combination with white bread or other unsuitable articles. Cream, and the lighter nuts, combine well with sweet foods, while oils, yolks of eggs, meat fats, and solid fats, combine well with foods which are rich in minerals and oxygen. People who are unable to furnish their table with expensive fats, such as butter, olives, cream, olive oil, bacon, eggs, eel and other delicacies, should use the cheaper forms of fats, as corn, oats, herring, walnuts, cream-cheese, cottonseed oil, bran, leaf lard, vegetable butter, middle rib of beef, blood and liver sausages. Meat products, prepared from the internal organs of the animal, are rich in lime and fat, and, if prepared from fresh meats of healthy animals, they are often preferable to canned and cold storage products, or to meat which hangs in a meat-shop for a week. However, every one who buys these articles should investigate the source and manner of preparation for himself. SUGAR. Artificial sugar is not a necessary article of food for the healthy individual who is able to supply his body with fresh and dried fruits the year round.