d64 



NEW ENGLAND FARMER. 



Dec. 



may most fully respond to one may not afford any 

 element for the others. 



Muscuhar effort involves the expenditure of 

 nervous force and of the substance of the muscle 

 itself, and consequently necessitates a restoration 

 of each. The abstraction of heat requires a new 

 supply of fuel. But that which may yield heat 

 in the animal system may yield neither muscle 

 nor nervous energy. 



A substance to be nutritious must yield to the 

 digestive forces some element that is needed in 

 the system. It may and in a few instances does 

 several ; but if it bestows none, then it is abso- 

 lutely useless in the animal economy. On the 

 other hand, any substance that readily supplies 

 the system with whatever is being continually 

 consumed becomes of essential value, even though, 

 from its inability to supply all the demands, it 

 cannot sustain life. 



The demands of the system being numerous 

 and variable, and each article of food yielding but 

 a few specific elements, it follows not only that 

 there must be some varietj-, but that, to be pro- 

 ductive of health and strength, this variation 

 must correspond precisely to the fluctuating con- 

 dition of the system. 



But as the wear of the frame as well as the ex- 

 penditure of the strength and nerve power in any 

 individual case may be assumed as quite uniform, 

 and the demand in these respects nearly constant, 

 while every month brings a temperature unlike 

 the preceding, it is manifest that the chief chang- 

 es required in nutrition are those to adapt the sys- 

 tem to the great annual change of temperature. 



I. — OF THE TEMPERATURE OF THE HUMAN BODY. 



While the external temperatui'e varies more 

 than a hundred degrees, the thermometer indi- 

 cates that in health the blood keeps invariably at 

 the same degree of heat. Neither the prostrat- 

 ing heat of summer nor the benumbing cold of 

 winter reaches the animal, vital warmth. This 

 fact, which is more or less well known, is general- 

 ly accounted for upon the vague but erroneous 

 impression that a living body has some mysteri- 

 ous power of preventing itself from losing its 

 heat. The jjower of a living body to generate 

 heat or to preserve it is no greater nor more mys- 

 terious than that of a stove. When the fire is 

 once started, each will keep Avarm so long as there 

 is a supply of fuel and no longer. The one is 

 combustion with flame ; the other, combustion 

 without flame. Chemically considered, the pro- 

 cesses are not only similar, but identical ; the 

 material consumed, the chemical action and the 

 results of the combustion being the same. Heat 

 can no more be generated in the animate body 

 without the consumption of fuel than in the inan- 

 imate. The living organization must, then, in the 

 cold season consume, and therefore by some means 

 be supplied with a large amount of fuel or heat- 

 generating food, in addition to that needful for 

 sustaining health and strength in the warm sea- 

 son. 



Having, then, the facts that the Avants of the 

 system in respect to the calorific or heating ele- 

 ment are variable, and that the various articles of 

 nutrition are equally or more variable in their 

 supply, it will be readily inferred that these ine- 

 qualities are intended the one to meet the other ; 

 that calorific or warming food is intended for win- 



ter, and non-calorific food for summer ; and not 

 only so, but that the heat-producing food in the 

 season of already oppressive warmth must prove 

 injurious, and that the non-calorific must be ex- 

 haustive and insufficient in the winter. 



But before we can properly enter upon a con- 

 sideration of the changes in food required by the 

 change of temperature, it will be necessary to 

 examine the chemical composition of food in 

 general. 



II. — OF THE CHANGES IN FOOD REQUIRED BY 

 THE CHANGE OF SEASONS. 



Thus far our inquiries in regard to food have 

 been limited to the question of the ordinary and 

 constant demand for healthful growth and action, 

 and to the proper supply. We are now prepared 

 to enter upon the consideration of the extraordi- 

 nary and fluctuating demands arising from the 

 change of seasons. 



The great heat-producing agent in the animal 

 economy is carbon, aided somewhat by hydrogen. 

 In the union of these elements with oxygen heat 

 is evolved, sometimes with a flame, as in the case 

 of burning wood, and sometimes without, as in 

 the case of most chemical action. What, there- 

 fore, is needed in the animal economy for the pro- 

 duction of heat is a supply of carbon, hydrogen 

 and oxygen. 



Recurring to the former table [which we have 

 omitted] of the proportion supplied by vegeta- 

 bles, we find an average deficiency of ten per cent, 

 carbon, eight hydrogen, and an excess of seven- 

 ty-seven in oxygen. 



Having thus already a large amount of oxygen 

 in the system unexpended, we have now to look 

 for substances containing a relative excess of car- 

 bon and hydrogen. 



Let us examine the fatty substances. The prox- 

 imate elements in the oils, lard, beef and mutton 

 suet, are oleine, stearine and margarin, of which 

 the proportions are : 



Carbon. Hydrogen. Oxysen. 



Miirgarin 46 46 7 



Stearine 47 47 6 



Oleine 46 44 8 



The diflferent degrees of hardness in different 

 fatty substances arise from variation of propor- 

 tion in the mixture, a preponderance of stearine 

 giving more solidity, and of oleine an opposite 

 quality. But whatever may be the proportion, 

 the elements are so slightly varied as to make no 

 appreciable difference in our present estimate ; 

 and we may hence take the average as the com- 

 position of oils, butter, fat meat, suet and pork. 

 This gives in fatty substances 46 carbon, 46 hy- 

 drogen, 7 oxygen ; reduced to weight, carbon 

 723, hydrogen 122, oxygen 155 pounds in a thou- 

 sand. 



Having already 168 pounds excess of oxygen 

 in the previous nutrition, we have, as fuel, 723 

 pounds carbon, 122 hydrogen and .323 oxygen. 



To consume this amount of carbon and hydro- 

 gen requires about 2000 pounds of oxygen, a 

 quantity much greater than ordinary food can 

 supply. _ 



Respiration here meets nutrition and restorea 

 the equilibrium. The air drawn into the lungs 

 freely imparts its oxygen, which combining with 

 the carbon and hydrogen, forms carbonic acid and 

 water, to be expired in turn — an interchange of 



