348 



THE FARMERS' REGISTER. 



not only of animal excrelions, but oC the various 

 parta ol' animal bodies also. This euperior etTeci 

 is in part explained by the fact, that ihey are all 

 richer in nitrogen, and during iheir decay, ihere- 

 Ibre, give ofi' a larger quantity oi' ammonia than 

 an equal weight oC any vegetable substance em- 

 ployed for food. But how does the animal matter 

 acquire this richness'? We inhale oxygen, but 

 no nitrogen, Crom the atmosphere — how, then, 

 is the vegetable matter changed in passing through 

 the animal'? What, in short, is the etlecl of the 

 digestive process upon our vegetable food 1 The 

 mystery is thus simply explained : 



" Animals have two necessary vital functions to 

 perform — to breathe and to digest. Both are ol 

 equal importance to the health and general welfare 

 of the animal. The digester (the stomach) re- 

 ceives the food, melts it down, extracts from it 

 what is best suited to its purposes, and conveys it 

 into the blood. The breathers (the lungs) sii't the 

 blood thus mixed up with the newly digested food, 

 combine oxygen with it, and extract carbon — 

 which carbon, in the form of carbonic acid, they 

 discharge by the mouth and nostrils into the air 



great processes — their eflCect upon the food that 

 remains in the body and has to be rejected Irom it, 

 is not difTicuk to perceive. 



" Suppose an animal to be full grown. Take a 

 full grown man. All that he eats as food is in- 

 tended merely to renovate or replenish his system, 

 to restore iliat which is daily removed from every 

 part of his body by natural causes. In the full 

 grown state, every thing that enters the body must 

 come out of the body in one lorm or another. The 

 first part ol" the lood that escapes is that portion of 

 its carbon that passes off from the lungs during 

 respiration. This portion varies in weight in 

 different individuals — chiefiy according to the 

 quantity of exercise they take. From five to nine 

 ounces a-d;iy is the average quantity, thougfi in 

 periods of violent bodily exertion thirteen to fifteen 

 ounces of carbon are breathed out in the form of 

 carbonic acid. 



" iSuppose a man to eat a pound and a half of 

 bread, and a pound of beef in twenty-four hours, 

 and that he gives ofi by respiration eight ounces 

 of carbon (^3500 grains) during the same time. 

 Then he has 



" Such is a general description of these two 



Carbon. Nitrogen. 



Taken, in his food, about 4500 grains, and 500 grains, while 



He has given off in respiration, 3500 and little or no nitrogen. 



Leaving to be converted into 

 food, or to be rejected 



1003 grains and 500 grains. 



" Our two conclusions, therefore, are clear. 

 The vegetable Ibod, by respiration, is freed from 

 a large portion of its carbon, which is discharged 

 into the air — nearly the whole of the nitrogen 

 remaining behind. 



" It is out of this residue, rich in nitrogen, that 

 the several parts of animal bodies are built up. 

 Hence the reason why they can be formed from 

 food poor in nitrogen, and yet be themselves rich 

 in the same element. 



" It is this same residue also, which after it has 

 performed its functions within the body, is dis- 

 charged again in the form of solid and liquid ex- 

 cretions. Hence the greater richness in nitrogen 

 — the greater fertilizing power of the dung of 

 animals, than of the food on which ihey live." — 

 Elements, pp. 171, 172. 



We here see how it is that the excretions of 

 animals, and especially of full grown animals, 

 should be richer in nitrogen than the vegetables 

 on which ihey are fied ; and the same reasoning 

 applies to the inorganic matter originally contain- 

 ed in the vegetable lood. As a whole, the food 

 is greatly diminished in weight during digestion, 

 but nearly all the nitrogen and (he whole of the 

 inorganic matter still remain in it, and therefore 

 it must be proportionately more influential as a 

 manure, in so far as its action depends upon either 

 of these constituents. 



Again, the study of the purposes served by the 

 food of animals, while it shows what a truly 

 nourishing vegetable food must contain, throws 

 much light also on what must necessarily enter 

 into the Ibod of plants, 



"Man, and all domestic animals, may be sup- 

 ported, may even be fattened upon vegetable food 

 alone— vegetables, therefore, must contain all the 

 substances which are necessary to build up the 



several parts of animal bodies, and to supply the 

 waste attendant upon the performance of the 

 necessarj' functions ol animal life. Let us con- 

 sider what thcee substances are, and in what 

 quantities they must be supplied to the human 

 body. 



"1. The food 7tiust supply carbon for respira- 

 tioT.. 



"A man of sedentary habits, or whose occu- 

 pation requires little bodily exertion, may respire 

 about five ounces of carbon in twenty-four hours; 

 cne who takes moderate exercise, about eight 

 ounces ; and one who has to undergo violent 

 bodily exertion, from twelve to fifteen ounces. 



" If we take the mean quantity of eight ounces, 

 then, to supply this alone, a man must eat eighteen 

 ounces of starch or sugar every day. If he take 

 it in the form ol wheaten bread, he will require 1| 

 Ibe. of bread, if in the form of potatoes, about 

 7^ lbs. of raw potatoes, to supply the waste caused 

 by his respiratory organs alone. 



" When the habits are sedentary, five Ibe. of 

 potatoes may be sufficient, when violent and con- 

 tinued exercise is taken, twelve to fifteen lbs. may 

 be too little. At the same time it must be observ- 

 ed, that where the supply is less, the quantity of 

 carbonic acid given ofi will either be less also, or 

 the deficiency will be supplied at the expense of 

 the body itself. In either case the strength will 

 be impaired, and fresh food will be required to 

 recruit the exhausted frame. 



" 2. The food must repair the daily waste of the 

 muscular part of the body. 



" When the body is full grown, a portion from 

 every part ol' it is daily abstracted by natural pro- 

 cesses, and rejected either in the perspiration or in 

 the solid and fluid excrements. This portion 

 must be supplied by the food, or the strength 



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