268 



THE ROTHAMSTED EXPERIMENTS. 



General 

 view of 

 results. 



Former 



conclusions 



confirmed. 



Fat-form- 

 ers the 

 regulating 

 factors. 



now those specially arranged to show the relation of con- 

 sumption to increase, at the same time include the amounts 

 required by the exigencies of respiration and maintenance. 



Taking a general view of the results, which is all that can 

 be done here, it is seen that where clover-chaff, with its large 

 amount of indigestible woody-fibre, was used as the ad libitum 

 food, the total amount of non-nitrogenous substance consumed 

 to produce a given increase in live- weight was much greater 

 than where the ad libitum food consisted of roots. Due 

 allowance must, therefore, be made for this in comparing the 

 results of one series with those of another. Doing this, it is 

 obvious that the amounts of really available non-nitrogenous 

 substances consumed were, at any rate much more nearly 

 uniform in the different series, and in the different pens, 

 than were those of the nitrogenous substance. Of the dif- 

 ferences that would still remain, most would be again reduced 

 by making allowance for the different respiratory and fat- 

 forming capacities of the remaining available non-nitrogenous 

 constituents; since, for example, much less of fatty matter 

 would be required than of starch or sugar, or of the pectine 

 compounds of the roots. 



Again, as in the case of the consumption by a given live- 

 weight within a given time, so now in that of the consump- 

 tion to produce a given amount of increase, there is a much 

 wider range of difference in the amounts of the nitrogenous 

 than of the non-nitrogenous constituents consumed ; and the 

 differences are, as before, much greater than can be explained 

 by the differences in the character of the nitrogenous sub- 

 stances which the figures represent in the different cases. 



Thus, then, the results of these experiments with sheep, 

 when interpreted with due regard to the known differences in 

 the character of the nitrogenous and non-nitrogenous con- 

 stituents in the different foods, fully justify the conclusions 

 drawn from them more than forty years ago — namely, that 

 taking food-stuffs as they go, it is their supply of the digestible 

 non-nitrogenous, that is of the more specially respiratory and 

 fat-forming constituents, rather than that of the nitrogenous 

 or specially flesh-forming ones, that regulates, both the 

 amount of food consumed by a given live-weight of animal 

 within a given time, and the amount of increase in live-weight 

 produced. 



But, as it seems to have been tacitly assumed in recent 

 years, since much attention has been paid to the investigation 

 of the digestibility of the different constituents of foods, that 

 conclusions founded on the determined amount in the foods 

 of the crude substances only cannot be relied upon, we have 

 had the whole of our early results, both with sheep and with 



