554 ME. J. B. LAWES AND DE. J. H. GILBEET OX THE C0:HP0SITI0X OF 
so far as Pectine, rather than Starch, may sei*ve for the formation of Fat, the amount of 
the dry substance of the food required directly to contribute to the increase, Avill be 
somewhat the greater. 
From the whole of the foregoing considerations bearing upon the relation of the con- 
stituents of increase to those of the food consumed to produce it, it appears, that a large 
proportion of the Fat, of which the increase of the so-called fattening animals so larply 
consists, may be formed in the body from other compounds of the food. ^ Of the nitrcr 
genous compounds, on the other hand, it is probable that frequently as little, and even 
less than 5 per cent, of the whole consumed, will be found finally stored up m the 
increase of the animal. Of the mineral matter of the food, a less proportion stm than 
of the nitrogenous compounds, will, especially in the case of Pigs, be thus retained in the 
increase. 
It is not the province of the present Paper, nor are the facts applicable to such a pur 
pose, to consider the chemical and physiological changes undergone, or the offices sub- 
served, by the— say 95 per cent, of the consumed nitrogenous compoimds in theri passage 
through the system. But, it may be remarked, that from the form m which a lai'gc 
proportion of them leaves the body, it is to be concluded that the) must have entered 
into its fluids, if not its solid structures, and therein been subjected to oxidation and trans- 
formation. That this must serve some essential purpose, even in the processes ol fat- 
tening animals subject to little muscular movement, there cannot be a doubt*. It is 
indeed certain, that if the animals are to store up as much as they can do of matters 
not containing nitrogen, a very large amount of nitrogen must pass thioiigh the bodt. 
compared with that which is finally retained in the increase. That this apparently 
excessive supply of nitrogenous compounds, independently of any mere influence on the 
activity of the functions or processes of the body, may itself yield up the elements tor 
the formation of Fat, is highly probable. 
Since it is found that by far the larger proportion of the solid increase of so-called 
fattening animals is really Fat itself— since it is probable that at least a great part o± the 
Fat formed in the body is normally derived from Starch and other ';?o??-nitrogenous con- 
stituents of the food, — and since the current fattening foods contain so very much iiioie 
of nitrogen than is eventually retained in the increase — it cannot be surprising, that the 
tendency of the results of all careful feeding experiments should be to shou , that the 
limit of applicability of the estimate of the comparative value of foods, according to 
tlreir percentage of nitrogenous compounds, is in practice very easily reached. I lac- 
tically, indeed, the amount of increase is much more frequently dependent on the pio 
portion in the food, of the digestible and assimilable «o«-nitrogenous compounds, than 
* We have found in the case of Pigs, that by far the larger portion of the niti'ogen consumed in the 
fattening food, passed off in the form of Urea. This was the case nith animals kept almost entirely u ithout 
movement ; and it was equally so, whether the food contained the proportion of nitrogenous to non-nitro- 
o-enous constituents, as in the Cereal grains ; or the much higher amount and proportion of the former, as in 
Leguminous seeds. 
