THE RELATIONS OF METABOLISM TO FOOD-SUPPLY. 167 
Lawes «Gilbert * at Rothamsted; in 1850, on the fattening of 
swine. ace yess ; 
Lawes & Gilbert's Investigations.—These experiments consti- 
tuted part of a series of feeding trials with fattening sheep and pigs, 
undertaken to test the then current view of Boussingault, according 
to which the feeding value of stock foods was proportional to their 
content of nitrogen. From the results of their extensive experi- 
ments, Lawes & Gilbert concluded that in fattening animals both 
the amount of food consumed by a given weight of animal within a 
given time and the increase in weight obtained are measurcd rather 
by: the supply. of non-nitrogenous than of nitrogenous constituents 
in the food. This fact of itself strongly suggests a production of 
fat from carbohydrates. 
In connection with these feeding trials investigations were also 
made into the composition of the increase in live weight during 
fattening.t By a comparison of the weight and composition of 
one of the fattened pigs with those of an animal supposed to be 
precisely similar at the beginning of the fattening the percentage 
composition of the increase was found to be approximately: 
NL have benah daha ereyaaaede tes ceca 28.61 
NST Gn cccecron to earer a gp pepe sea IE NU al ora ES EE 0.53 
Proteids ENG do leh eda dene aos eT ae he 7.76 
fF) ae eet ae Cae RENE pete e eee 63.10 
100.00 
During the ten weeks of the fattening the animal gained 88 
pounds, containing according to the above figures 55.5 pounds of 
fat, while the total food consumed contained but 13.7 pounds. In 
other words, over three fourths of the fat was formed from other 
ingredients of the food. ’ 
After the publication of Voit’s first paper, Lawes & Gilbert t 
presented the results of this and eight other experiments in their 
* Report British Association Adv. Sci., 1852; Jour. Roy. Agr. Soc., 14, 
459; Rep. British Asso. Adv. Sci., 1854; Rothamsted Memoirs, Vol. II. 
+ Jour. Roy. Agr. Society, 21, 465; Phil. Trans., Part II, 1859, p. 493. 
} Rep. British Asso. Adv. Sci., 1866; Phil. Mag., Dec., 1866; Rotham- 
sted Memoirs, Vol. IV. 
