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FOODS, IN RELATION TO RESPIRATION AND FEEDING. 341 
pens one of the animals died—we shall see, when we come to consider the 
question of the amount of increase produced by a given amount of food con- 
sumed, that although the pigs were satisfied to eat a smaller proportion of 
food in relation to their weight in these pens where the proportion of nitrogen 
was comparatively large, yet the proportion of increase to the food consumed 
was less than where the amount of zon-nitrogenous substance consumed 
was much greater. Hence, in these cases, if there were a smaller amount 
of food consumed, there was also a smaller proportion of increase produced 
by it, and there would therefore at the same time obviously be a larger 
proportion of it available for the purposes of respiration. These apparent 
exceptions are not, then, necessarily adverse to the view that the respiratory 
process was the gauge of consumption. 
We have already noticed, that notwithstanding the weather was much hot- 
ter during the progress of the second series of experiments, yet that there 
was here, upon the whole, a larger amount of non-nitrogenous substance 
consumed in proportion to weight of animal than in the first. ‘This apparent 
excess, if indeed it show any real excess in respiratory and fat-forming equi- , 
valent, at any rate does not do so in the degree which the bare figures of the 
Table would indicate. Thus, the Indian corn of the first series, of which 
a less amount seems to have sufficed than of the barley in the second, con- 
tained about 6 per cent. of oleaginous matter, instead of less than 3 per cent., 
as in the barley. And as a deficiency of 3 per cent. in fatty substance would, 
for respiratory and fat-forming purposes, require to be substituted by about 
twice and a half that amount of the other non-nitrogenous constituents, it 
is obvious that the respiratory and fat-forming capacity of the Indian 
meal non-nitrogenous matter was therefore somewhat higher than that of the 
barley ; and hence a less amount of it would be required to produce the same 
result. 
We could add to the results already given those of further experiments 
both with pigs and sheep, as well as some with bullocks, bearing upon the 
point we have been considering; but those we have already adduced are, 
we think, sufficient to justify our conclusion, that, in reference to this first 
question, at least so far as fattening animals are concerned, the amount of 
food consumed is regulated more by its supplies of the non-nitrogenous, than 
of the nitrogenous constituents. 
We now come to the second question; namely, that of the relationship 
of the inerease in live weight produced to the consumption of nitrogenous 
and non-nitrogenous constituents in the food. 
Turning firstto the experiments with sheep, we have in Table V. the amounts 
respectively of the non-nitrogenous, of the nitrogenous, and of the total or- 
ganie substance consumed to produce 100 Ibs. inerease in live weight. 
In viewing the Tables in reference to this point, we must, as before, read 
the indications of the actual figures as modified by the obviously different 
capacities for the purposes of the animal ceconomy of the substances, the 
amounts of which they in each ease represent. Especially, too, when con- 
sidering the results with the sheep, we must bear in mind the fact, which we 
have ascertained by direct experiment, namely, that other things being equal, 
the more succulent the food, the less will be the proportion of real dry sub- 
stance in the increase obtained by its means; and also, that the greater the 
amount of fat produced the greater considerably will be the per-centage in 
the gross increase of real dry substance. And we must further remember, 
that as in the Tables showing the relationship of conswmption to respiration, 
the figures also included the increase in weight obtained, so now, in the 
Tables professing to show the relationship of the izcrease to the constituents 
