Dietaries.--The best proportions of proteids, carbo-hydrates and fats required for the nourishment of the body has not yet been conclusively decided. The common plan is to average the dietary of large bodies of persons, particualrly of soldiers and prisoners. These dietaries have been adjusted empirically (the earlier ones at least), and are generally considered as satisfactory. They are chiefly of English and German origin. Another method is to laboriously analyse the injesta or food consumed and compare it with the dejecta or excretions, until a quantity and kind of food is found which is just sufficient to keep the body in equilibrium. This latter plan is the best, but to be quite satisfactory must be tried on a large number of suitable persons under varying conditions, both of quantity and kind of food. Nearly all the experiments have been made on persons accustomed to a stimulating dietary: their usual food has included a considerable quantity of flesh and alcoholic drinks. Sufficient attention has not been paid to the dietaries of the more abstemious races who partake of little if any flesh food. The standard daily dietary for a man of average weight, doing a moderate amount of work, is variously stated by the best authorities as proteids from 100 to 130 grammes, fat 35 to 125 grammes, and carbo-hydrates 450 to 550 grammes. There is a surprising difference of opinion on the amount of fat, but those who give least fat give the largest quantity of carbo-hydrate and _vice-versa_. Dr. R. Hutchison in "Food and Dietetics," sums up the quantities given by the highest authorities as follows:--- Proteid 125 g. ( 4.4 oz.) x 4.1 = 512 cal. = 20 g. N, 62 C Carbo-hydrate 500 g. (17.6 oz.) 4.1 2050 200 Fat 50 g. ( 1.8 oz.) 9.3 465 38 ----------------- ---- -------- ----- 675 g.(23.8 ) 3027 Total 20 g. N, 300 C The nutrient ratio is 1 : 4.9. For scientific purposes, metrical weights and measures are used, instead of the inconvenient English grains, ounces, pounds, &c. (1 gramme = 15.43 grains; 1 ounce avoirdupois = 437.5 grains = 28.35 grammes). A calorie is a measure of the power of a food in generating heat and muscular energy (these two being convertible).