ABSTRACT
Chemistry and physiological experimentation have vied with each other during the last 25 years in adding to knowledge of the functions of life and in thus extending the range of preventive medicine. The discovery by Starling and Bayliss of hormones has thrown great light on many processes affecting health. Vitamins have been described by Cramer as 'food hormones', and this appears to be their natural position. An adequate amount of protein, carbohydrates, fat and salts is also a vital necessity of health. Indeed until recent years it had been assumed by Voit, Pettenkofer, and other investigators that these four substances and water included all that was essential for normal growth and health. The effect of cooking on vitamins has been made the subject of investigation. It has been noted that the amount of each of them which is essential for life is minute, but they are all easily destroyed by heating in the presence of air.
