38 ABSOLUTE QUANTITY OF FOOD. 



lous disease. It is evident that a control over these affections may be ob- 

 tained, or even their cure, to a considerable extent, accomplished, by suit- 

 able changes in the nature of the food. This is strikingly seen in the 

 improvement of the health of sailors during long voyages, since the intro- 

 duction of vegetable preparations or acid juices. In 1726, Admiral Ho- 

 * sier sailed from England to the West Indies with seven ships of the 

 line, and lost his whole crew twice by scurvy. The circumnavigation 

 of the globe is now often accomplished without the loss of a single man. 



I have already remarked the insufficiency of the tables setting forth 

 the value of articles of food as dependent on their chemical constitution. 

 Such tables are of little use, agriculturally, in the case of animals, and 

 still less, physiologically, in the case of man. The art of cooking does 

 not minister alone to the gratification of the palate, it lends a real assist- 

 ance to the operation of digestion. New elements may not have been 

 added, nor existing ones removed in submitting the food to the action 

 of a high temperature, yet such a change is thereby impressed upon it 

 that it becomes more capable of digestion, and more subservient to the 

 wants of the economy. 



In determining the absolute quantities of nutrient substances required 

 The absolute ^7 * ne system, Lehmann observes that there are three mag- 

 quantity of nitudes which we are especially called upon to consider : the 

 first is, the quantity of food requisite to prevent the animal 

 sinking from starvation ; the second is, that which affords the right sup- 

 ply of nourishment for the perfect accomplishment of the functions ; and 

 the last is, that which indicates the amount of nutrient matter which 

 may, under the most favorable circumstances, be subjected to metamor- 

 phosis in the blood. The method of finding the minimum of food nec- 

 essary to support life by stopping all supplies without, and determining 

 the quantities of matters which the organism uses by the excretion of 

 urine, fasces, expired and transpired products, though it has yielded re- 

 sults of the utmost importance to science, is nevertheless not altogether 

 reliable, for in such a state of inanition the system is brought into a 

 morbid condition, or, at all events, is not acting in'a normal way. More- 

 over, much depends on the activity with which the various functions are 

 carried forward, a necessity for nourishment increasing with increase of 

 external activity. And as to the amount of food demanded for the 

 maintenance of the system at its standard, it must be borne in mind 

 that of the four classes, the carbohydrates, the fats, the albuminous mat- 

 ters, and the salts, no one alone will answer the purpose, but all must 

 be employed together, and this in variable proportion, according as the 

 local, and therefore variable, wastes of the system may have been. These 

 considerations indicate how complicated the problem we have in view 

 really is. 



