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KIDD'S OWN JOURNAL. 



we cannot do better than have recourse to 

 experience; since science may here, as in 

 many other problems it has successfully 

 done, evolve from the practical experience 

 of mankind the causes of many unexplained 

 phenomena. These considerations induced 

 Dr. Lyon Playfair to have recourse to the 

 statistics of diet procurable from the various 

 public establishments of the kingdom, as well 

 as other sources ; since these dietaries are the 

 result of careful observation and prolonged 

 experience of the amount of food of known 

 weight, quality, and description, found to be 

 requisite for the support of man under every 

 circumstance of age, condition, and employ- 

 ment ; and he has endeavored, by analysing 

 that experience, to acquire an insight into 

 the processes of nutrition, under given con- 

 ditions of life, otherwise unattainable in the 

 present state of our knowledge. To do this, 

 however, is no slight task ; and the result of 

 much labor makes but a sorry show. For 

 instance, to gain the result afforded by our 

 pauper dietaries, 542 unions were applied to ; 

 700 explanatory letters were written to them ; 

 and 54,564 calculations, including the ad- 

 ditions, had to be made, in order to educe 

 results which occupy but a single line in a 

 dietary table. 



There is • no longer any question of the 

 heat of the body being due to the combustion 

 of the unazotised ingredients of food; the 

 butter, starch, fat, &c, which we eat, being 

 just as truly burnt as if they had been thrown 

 into the fire, or used for candles. A man 

 annually inspires about seven hundredweight 

 of oxygen; one-fifth of which, we may say, 

 combines with, that is, burns a portion of his 

 body, and produces heat ; and were it not 

 for the introduction of fresh fuel, or, in other 

 words, food, the whole of the carbon in the 

 blood would be consumed in about three 

 days. The amount of food required depends 

 on the number of respirations, the rapidity 

 of the pulsations, and the capacity of the 

 lungs. Cold increases the amount of oxygen 

 inspired by a man, whilst heat diminishes it. 

 We see the influence of temperature on the 

 amount of food required by the inhabitants 

 of the Arctic Regions, and of the Tropics, re- 

 spectively ; thus, an Esquimaux consumes 

 weekly about 250 ounces of azotised ingre- 

 dients (flesh, &c), and 1280 ounces of un- 

 azotised substances (fat, oil, &c), containing 

 no less than 1125 ounces of carbon; a 

 prisoner at hard labor in Bengal consumes 

 but 28 ounces of azotised food, and 192 of 

 non -azotised, containing 91 ounces of carbon. 

 The case of the Esquimaux may be an ex- 

 treme one, and the anomaly is often met 

 with of the natives of the Tropics showing a 

 predilection for fatty food, which most 

 abounds in carbon; still the differences in 

 the quantities consumed are enormous. 



More than a century ago, Beccaria pointed 

 out the nature of the second great division 

 of articles of food, viz., those resembling, or 

 actually being, flesh ; and asked, " Is it not 

 true, that we are composed of the very sub- 

 stances which serve for our nourishment?" 

 A simple view, which now meets with general 

 belief; for the albumen, glutpn, casein, &c, 

 are now recognised as the sole flesh-formers ; 

 whether the immediate source of these proxi- 

 mate constituents of flesh and sinew be in- 

 direct, from the flesh of the animal, or direct 

 from the azotised constituents of the vege- 

 table food. The graminivorous animal is but 

 a granary for the carnivorous, and for f-uch 

 as man, feeding indifferently on vegetables 

 or flesh. The flesh-forming principles of the 

 corn, grasses, and roots, eaten by the first, 

 are deposited during the process of nutrition, 

 as flesh, sinew, &c. ; this deposition accu- 

 mulates with the growth of the animal, and 

 is, when eaten, directly assimilated by man, 

 and those animals which feed on flesh. 



The mere weight of food eaten is no 

 criterion of its nutritive value, either as a 

 flesh-former, or heat-giver; thus, whether 

 a sailor, R.N., is fed on fresh or on salt 

 meat, the weight varies very slightly, being 

 302 ounces of fresh meat diet to 290 of the 

 latter per week ; but, with the former, he 

 obtains less than 35 ounces of flesh-formers, 

 and 70^ ounces of heat-givers, whilst the salt 

 dietary gives him nearly 41 ounces of flesh- 

 formers, and 87^ ounces of heat-givers ; a 

 difference in the nutritive values of dietaries 

 of similar weights, which pervades the tables 

 Dr. Playfair has constructed. 



Practice, as exemplified in a comparison of 

 various public dietaries, shows considerable 

 differences in the nutritive value of the food 

 consumed by the adult, the aged, and the 

 young. Our soldiers and sailors — types of 

 healthy, adult men, consume about 35 ounces 

 of flesh-formers, to 72 ounces of heat -givers per 

 week; the ratio of the carbon contained in them 

 being as 1 in the first, to 3 in the second. Aged 

 men require less flesh-formers, 25 to 30 

 ounces, and more heat-givers, 72 to 78 ounces; 

 the respective ratios of the carbon being as 

 1 to 5 in this case; whilst with boys of ten 

 to twelve years old, the amount of flesh- 

 formers given is about half that of the adult, 

 17 ounces, the heat givers being 58 ounces — 

 the ratios of the carbons being nearly 1 to 5^. 

 Warmth and protection from the weather 

 diminish the necessity for food ; exposure 

 and hard labor increase it ; and, bearing these 

 conditions in mind, Dr. Playfair's table of 

 dietaries is a painful one. The average value 

 of the pauper diet of all the English counties 

 in 1851, was 22 ounces weekly of flesh- 

 makers, and 58 ounces of heat-givers ; that 

 of prisoners in England, sentenced to hard- 

 labor for more than four months, 20£ ounces 



