80 THE CONNECTICUT AGRICULTURAL 



animal tissues (albuminoids) to the extent of some fifteen per cent, 

 of their dry matter. 



The carbhydrates cannot restore the worn out muscles or mem- 

 branes of the animal any more than coal can be made to renew 

 the used-up packing, bolts, valves, flues and gearing of a steam- 

 engine. The albuminoids are to the ox or the man what brass 

 and iron are to the machine, the materials of construction and 

 repair. 



The carbhydrates are, furthermore, to the animal very much 

 what coal and fuel are to the steam-engine. Their consumption 

 generates the power which runs the mechanism. Their burning 

 (oxidation) in the blood of animals produces the results of life just 

 as the combustion of coal in the fire-place of the steam-engine pro- 

 duces the motion and power of that machine. 



There is, however, this diflerence between the engine and the 

 animal. The former may be stopped for repairs, the latter may 

 run at a lower rate, but if it be stopped it cannot resume work. 

 Hence the repairs of the animal must go on simultaneously with 

 its wastes. Therefore, the material of which it is built must 

 admit of constant replacement, and the dust and shreds of its 

 wear and tear must admit of escape without impeding action. 

 The animal body is as if an engine were fed with coal and water 

 not only, but with iron, brass and all the materials for its repair, 

 and also is as if the engine consumed its own worn out parts, 

 voiding them as ashes or as gas and smoke. The albuminoids, or 

 blood- and tissue-formers, are thus consumed in the animal, as 

 well as the carbhydrates, or fuel proper. The fact that the albu- 

 minoids admit of consumption implies that when the carbhydrates 

 or proper fuel are insuflicient, they, the albuminoids, may them- 

 selves serve as fuel. Such is the case, in fact. But, nevertheless, 

 the two classes of substances have distinct offices in animal nutri- 

 tion, and experience has demonstrated, that for each special case 

 of animal nutrition a special ratio of digestible albuminoids to 

 digestible carbhydrates is the best and most economical, and, 

 within certain limits, is necessary. This proportion we designate 

 as the nutritive ratio, and these explanations make its significance 

 evident. 



To allow of directly comparing the money-value of feeding 

 stuffs with some universally accepted standard, the last column of 

 the table (page 81) gives a comparison with good average meadow 

 hay taken as 1. 



