478 



THE FARMER'S MAGAZINE. 



FOOD AND MANURES, 



In the descriptions that are now made of organic 

 bodies that are used for food and ai)j)lied as ma- 

 nures, there is always given, along with the natural 

 properties and practical value of the article, the 

 chemical analysis of the bodies, which shows the 

 value of the composition in the number and quality 

 of the constituent principles. But every theory 

 yet advanced on this point, has been proved to be 

 wholly fallacious, by means of the truths of prac- 

 tical experience. The most recent scientific ar- 

 rangement of the constituent parts of organic 

 bodies places the elements in two divisions : — 

 Nitrogenous, or flesh-forming principles ; non- 

 nitrogenous, or free from nitrogen, and producing 

 respiration, heat, and fat. Among the latter, starch 

 is abundant, with sugar, gum, fat, wines, beer, 

 and spirits. The former, or the strictly nutritive 

 substances, contain vegetable albumen, fibrin, and 

 casein, with animal flesh and blood. A third class 

 comprehends the inorganic substances — water, 

 salts,iron, &c. All food is thus nitrogenous (or nutri- 

 tive and flesh-forming) or non-nitrogenous (or 

 heat-making). 



This brilliant fallacy has obtained almost the 

 entire possession of physiologists, who decided 

 that the percentage of nitrogen, large or small, in 

 alimentary substances, affords a correct estimate 

 of the value, except where gelatine enters very 

 largely into the composition. This division of 

 food meets with no objection, as it is a chemical 

 fact : but the presence of nitrogen being made the 

 test of value, and all albuminous substances form- 

 ing an essential proportion of organized tissues, 

 a striking example is seen of chemical reasonings 

 applied to physiology, which a simple confrontation 

 with nature suffices to upset. Albuminous sub- 

 stances are certainly present ; but a larger quantity 

 is essential in non-nitrogenous matters, as oil and 

 salts. Wheat contains only 2.3 per cent, of nitrogen; 

 whereas beans contain as much as 5.5 per cent.; 

 lentils 4.4, and peas 4.3 percent.; and yet, with 

 this inferiority in the quantity of nitrogen, wheat 

 is very remarkably superior in nutritive value to 

 the latter plants. In this case, exjicrience flatly 

 contradicts the standard that is applied. It is well 

 known that in the animal kingdom no two organ- 

 isms of the very same kin and descent jjosscss an 

 equal capability of assimilating the same sub- 

 stances; and it may bo inferred that vegetal)les 

 are similarly endowed. Vital phenomena depend 

 on processes that cannot be explained by che- 

 mi-itry, and may be su])posed to be very unlike 



the processes of our laboratories, and demand 

 other tests. 



"From higher judgment seats, make no appeal 

 To lower." 



Such is the appeal now made from jjhysiology 

 to chemistry. The chemists may proceed with 

 their labours, analyzing, weighing, experimenting, 

 and propounding hypotheses : no doubt much 

 aid will be obtained ; but no physiological problem 

 will be solved, though it may leave the hope of 

 doing more. Physiology must employ chemistry 

 as an assistant to analyze — fat, for instance ; but 

 not to trouble with any hypothesis about the part 

 played by fat in the organism, or how itself is pro- 

 duced. The assistance of chemistry is indispen- 

 sable to the vital laboratory of physiology, as a 

 means of explanation, not of deduction ; as a pil- 

 lar, not a pinnacle; an instrument, not an aim. 

 The two laboratories are most diametrically oppo- 

 site, and admit no unanimity or precision. 



Chemical analysis may conduct to the threshold 

 of life, but there all its guidance ceases. A new 

 order of complications intervenes ; a new series of 

 laws has to be elicited. Chemistry is only able to 

 say of what elements any substance is constructed, 

 not how the agency is performed. Any attempt to 

 explain the nutritive value of articles as food, by 

 an enumeration of its constituents, must belong 

 to "the physiology of probabilities." The cardi- 

 nal rule is ever violated in our gropings towards 

 the light — " Never attempt to solve the problems 

 of one science by the order of conceptions peculiar 

 to another." Every art and science has its own 

 peculiar conceptions and philosophy, by which it 

 is understood and advanced. The knowledge is 

 indispensable of the i)hysical and chemical laws 

 that are implied in the vital processes ; but over 

 and above, there are the specific laws of life, which 

 cannot be deduced from physics and chemistry. 



The nitrogenous theory has yielded tlie acknow- 

 ledgment, that nitrogen is nutritive "only" in pe- 

 culiar combinations. The consequence is inevitable. 



The proportion of plastic and non-plastic mate- 

 rials, or of nitrogen and the absence of it, has 

 only to be observed in many cases, and the result 

 never fails to pronounce against the theory of di- 

 vision. In rice the ratio is 10 to 123, in beef 10 

 to 17, requiring ten pounds of rice to one of beef 

 to obtain the flesh-forming materials; and then, 

 how dispose of the vast quantity of respiratory 

 materials ? The body would be entirely burnt up 

 by such an enormous heat, which does nut seem 



