274 THE ROTHAMSTED EXPERIMENTS. 



Established In conclusion in regard to this branch of the subject : — it 

 c s ^^ u ' must be considered established, that, taking ordinary food- 

 stuffs as they go, neither the amount consumed in relation to 

 a given live-weight of the animal within a given time (which 

 of course in the fattening animal covers the requirements for 

 increase as well as for sustenance), nor the amount consumed 

 to yield a given amount of increase in live-weight (which 

 covers the requirements for sustenance also), was at all in 

 proportion to the amount of the nitrogenous constituents 

 supplied. It is, on the other hand, obvious that the con- 

 sumption, both for sustenance and for increase, was much 

 more nearly in proportion to the amount of the digestible 

 and available non-nitrogenous constituents supplied ; but, 

 that it was more nearly still regulated by the amount of the 

 total digestible organic substance — nitrogenous and non-nitro- 

 mtrogen- genous together — which the foods supplied. The indication 

 ous and j„ indeed, as will be more clearly seen further on, that, if 



non-nitro- ? , * - . .. ., , , J . .' 



genous sub- there be a deficiency ot available non-nitrogenous constitu- 

 stances as en t s an exce ss of the nitrogenous may to a certain extent 

 for each take the place of the non-nitrogenous ; that, in fact, within 

 other. certain limits, the two classes of constituents may, for the 



purposes of respiration and fat-formation, mutually replace 



each other. 

 Respir- When the character of the main products of respiration, 



atorypro- an( j the prominence, in a quantitative sense, of the respiratory 



dlCCtS CLThClt 



respiratory function in the maintenance of the body, are considered, it 

 function, seems only what might be expected, that the consumption by 

 a given live-weight of animal within a given time should be 

 regulated, more by the supplies in the food of the oxidable 

 non- nitrogenous, than of the nitrogenous or more specially 

 flesh-forming constituents ; and now that it is known, as will 

 further on be shown is the case, that in the exercise of force 

 the respiratory action is enormously increased, whilst that of 

 nitrogenous transformation is but little augmented, the result 

 is rendered still more consistent and intelligible. 



That the increase in live-weight of the animal should 

 (provided the food be not abnormally poor in nitrogenous 

 substances) also be regulated more by the supplies of the 

 non- nitrogenous than of the nitrogenous or flesh-forming con- 

 stituents, does not at first sight seem so intelligible. 

 Relative There is, however, no doubt of the fact, that our current 



nttr 6 °^ fattening rations are, as such, more valuable in proportion to 

 and non- their richness in digestible and available non-nitrogenous, 

 nitrogenous than to that of their nitrogenous constituents. At the same 

 as food and time, as the manure is valuable largely in proportion to the 

 'manure. nitrogen it contains, there is, so far, an advantage in giving a 

 food rich in nitrogen, provided it is in other respects a good 



