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446 PRINCIPLES OF ANIMAL NUTRITION. 
before, OG represents the fasting metabolism at a temperature 
below the critical point and OM the critical amount of food at this 
temperature. Then the line GKS represents the availability of 
the food, HLS’ the heat production, and OS the maintenance 
requirement. Beyond the point S we may assume that the net . 
availability of the food remains the same, represented by the line 
ST. But a fraction of this net available energy, however, can be 
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recovered as mechanical work, and its utilization will therefore be 
represented by some such line as SV, while the heat production will 
be correspondingly increased as represented by S’V’. Similarly 
the proportion of the net available energy which in the quiescent 
animal is stored up in the form of new tissue may be expressed by 
a line SU and the corresponding heat production by S’U’. What 
the relation between the proportions utilized in the two cases is we 
do not know, and the diagram is intended to be simply schematic; 
