Tea is diuretic, stimulating the action of the kidneys. Through its stimulant action it relieves fatigue and has been found especially useful in Arctic explorations and for soldiers on long marches. When taken hot it will often relieve sick headache. When taken on an empty stomach, after a long fatiguing tramp or a prolonged “shopping” excursion, its refreshing effect may be felt for an hour or two. The ease of its preparation and the quickness of its effect tends to produce the “tea habit.” When drunk to excess with meals, it causes the precipitation of the ferments in the digestive juices, retards digestion, and may cause constipation, particularly if taken after long infusion. Strong tea has an overstimulating effect on the nervous system which reacts, producing depression and restlessness; this may lead to insomnia, muscular twitchings, and palpitation of the heart. Habitual users often take from ten to twenty cups of strong tea daily; in these the evil effects of the tea habit are easily noted. Americans, or any people whose nerves are highly stimulated, from the stress of life, or from habitual nerve tension, should particularly avoid all stimulating beverages. Poor tea, because of the greater amount of tannin it contains, produces its ill effects more quickly. From overstimulation of the nervous system, poor tea, long stewed, has been held to be a contributing factor in insanity. Tea should be avoided by the dyspeptic, by those of constipated and flatulent habit, or by the anemic. Tannin coagulates the albumin in milk or cream and the addition of these to tea renders it more indigestible; plain or with lemon juice it may be well borne by those with whom it disagrees when used with cream or sugar. _Thein_, the active principle in tea, is chemically identical with caffein in coffee. * * * * * [Sidenote: Coffee] Coffee is prepared from the seeds of the coffee tree. The best known brands come from the Island of Java, Mocha, Rio de Janeiro, and Mexico. Coffee, like tea, _is not a food_, it is a stimulant. The active principle is caffein. This is an alkaloid and is a strong stimulant to the central nervous system. It quickens the heart action, and the stimulating effect is so apparent with many, that they cannot sleep for several hours after drinking it. Others drink coffee to quicken mental activity and to keep them awake. It must be borne in mind, however, that there is a reactionary effect from all stimulants, and while coffee is not intoxicating, as alcohol, it has a similar effect on the nerves and heart. Coffee has the redeeming feature of having a pleasing aroma, which, because of the effect on the mind, may incite the flow of gastric juice. Despite the fact that no morning beverage has quite the same pleasing aroma, or pungency, ordinarily one is much better without it. Coffee stimulates the action of the heart and for this reason it is used in collapse to restore heart action.