DIETETICS 619 



with the gastric juice, and therefore when taken by the mouth, retard 

 the proteolytic action, so that any favourable effect on the secretion of 

 the juice may easily be lost in the subsequent digestion, unless the 

 alcohol is dilute (Chittenden and Mendel). The action of alcohol intro- 

 duced into the rectum on the gastric secretion is both reflex and direct. 



(5) Alcohol is of no use for healthy men. 



(6) Alcohol in strictly moderate doses*, properly diluted and especi- 

 ally when taken with the food, is not harmful to healthy men, living 

 and working under ordinary conditions. 



(7) Modern experience goes to show that in severe and continuous 

 exertion, coupled with exposure to all weathers, as in war and in 

 exploring expeditions, alcohol is injurious, and it is well known that it 

 must be avoided in mountain climbing. 



Alcohol in small doses, when given by the stomach or (in animals) 

 injected into the blood, causes stimulation of the respiratory centre and 

 increase in the pulmonary ventilation. In man, this increase usually 

 amounts to 8 to 15 per cent., but is occasionally much greater. But the 

 limit which separates the favourable action of the small dose from the 

 hurtful action of the large, is easily overstepped. When this is done, 

 and the dose is continually increased, the activity of the respiratory 

 centre is first diminished and finally abolished. In dogs, for instance, 

 after the injection of considerable quantities of alcohol into the stomach, 

 death takes place from respiratory failure, and the breathing stops 

 while the heart is still unweakened (Fig. 85, p. 189). This is the final 

 outcome of a progressive impairment in the activity of the centre, of 

 which the slow and heavy breathing of the drunken man represents an 

 earlier stage. 



Tea, coffee, and cocoa are more suitable stimulants for healthy 

 persons, because they are less dangerous than alcohol, and they 

 leave no unpleasant effects behind them. But it should be remem- 

 bered that there is no stimulant which is not liable to be abused. 

 It has been shown by ergographic experiments (p. 726) that, like 

 alcohol, tea, coffee, mate, and cola-nut, which all contain the alka- 

 loid theine or caffeine, restore the power of performing muscular 

 work after exhaustion, but only if food has been recently or is 

 simultaneously taken. 



Vitamines. Certain substances, although neither in the ordinary 

 sense foods nor condiments, seem to be necessary for the main- 

 tenence of health, for in circumstances in which these cannot be 

 obtained for long periods so-called ' deficiency diseases,' such as 

 scurvy, are liable to occur. Scurvy used to be the scourge of the 

 sailing-ship in the days when fresh meat, and particularly fresh 

 vegetables and fruits, were unobtainable on long voyages. It has 

 long been known that it is prevented by the use of lime or lemon- 

 juice, in which citric and a trace of malic acid are contained, and 

 it used to be thought that it was the organic vegetable acids which 

 were the important thing. Recent researches have shown, how- 

 ever, that scurvy is only one of a group of diseases, including beri- 

 beri, and probably pellagra, rickets, and others which are induced 



* Not more than l oz. of absolute alcohol, corresponding to about 4 oz. of 

 whisky, or 2 to 3 wineglasses of sherry or port, or a pint of claret, or a couple 

 of pints of light beer in 24 hours. 



