The lemon is the fruit of a tropical or subtropical tree, belonging to the Orange family (Aurantiaceae). It is oblong in shape, with a protruding point at each end. The fruit is from two to four inches long, and when ripe is of a bright yellow color, slightly tinged with green. It contains no nutriment to speak of; the juice is very acid, and for this reason is highly valued for making drinks in hot weather, being especially valuable for fever patients. The citric acid which the lemon contains acts as a disinfectant in the stomach, killing the germs, and doing away with stomach washes. Very much lemon-juice should not be taken at meal-time, as acids, if taken in any considerable quantity, hinder the digestion of starch, by changing the saliva, which is alkaline, to an acid. For this reason lemon pies, puddings, cakes, and all other foods where starch is combined with the lemon, are not to be recommended. But egg-nog, made of the white of the egg and lemon-juice is all right, as the white of the egg contains only albumen.