To take a somewhat extreme example. The mention of such homely, old-fashioned, domestic remedies as black-currant tea for a bad cough, or soap and sugar plasters for a boil--genuine relics from our grandmothers--now usually excite a smile of derision; nevertheless they have been instanced by one of our most able living pathologists[120] for their admirable adaptation to their purpose, and have been shown to rest upon a hitherto unsuspected basis of physiological therapeutics. Another illustration may be drawn from the nursery tradition that bad temper is often effectually cured by a dose of rhubarb.[121] Carefully conducted observations upon children confirm the conventional connection of peevishness with disordered digestion. It has been found that gastric indigestion produces oversensitiveness, fretfulness, and irritability, while chronic constipation results in erratic conduct, stupidity, languor, headache, and moodiness. These effects may be so far-reaching that, for no other reason than chronic constipation, children may lose a large proportion of the advantages provided in school life; they may even run the risk of being classed as "backward," from the interference with mental progress of the food poisons reabsorbed into their circulation. Modern methods of child training lay great emphasis upon the prevention of these or kindred conditions by early formation of good habits; or, when carelessness necessitates curative treatment, our old nurse's panacea of drugs is the last resort; the first consists in attempts to re-establish normal functions by the more natural means of suited food and special exercise. It is time, too, that the so-called "hardening fallacies," responsible for the maiming of countless lives, were finally exposed and exploded. The idea, for example, dies hard that beneficial endurance is cultivated by exposure to cold; therefore, bare necks, arms and legs are lauded as means of developing a Spartan spirit in young children. Now no profound study of hygiene is required to demonstrate the close interdependence of warmth with growth and nutrition, or to show that the chilly and underclothed, sedentary child is both stunted and starved; whereas the suitably clothed and freely active child is able to carry on unhampered the necessary processes of growth and development.[122] So important is warmth to the infant, that _eighty per cent._ of the total energy derived from its food is utilised for the maintenance of the body temperature essential to growth and for the activities of the organic and muscular systems.