THE RELATIONS OF METABOLISM TO FOOD-SUPPLY. 159 
of the fasting animal. The material lowering of the quotient which 
was observed was therefore interpreted as showing that the sodium 
butyrate was oxidized; and this conclusion was confirmed by the 
strongly alkaline character of the urine and the absence from it 
of butyric acid. The amount of sodium butyrate injected during 
1} to 1} hours was sufficient in the several experiments to supply 
from 60 to 100 per cent. of the respiratory demand of the fasting 
animal. If this had been oxidized uselessly—that is, if the energy 
liberated had not been of use to the organism—then the consump- 
tion of oxygen and elimination of carbon dioxide should have in- 
creased correspondingly. This, however, was far from being the 
case, as the following fifteen-minute averages for the periods 
before, during, and after the injection show: 
sa - Carbon... was 
Acid Oxygen Dioxid Respira- 
Teyentod. [Conmumed,| eoreted, | ut at 
Animal I, weight 1.92 kgs.: 
Before injection ear ecatite ie aa cdemiadiedvall Cures 260.9 196.1] 0.75 
During: “S etka tyaele ere 28 0.133 280.0 190.5 0.68 
After a ee ee 253.3 181.2 | 0.71 
Animal II, weight 1.9 kgs.: 
Before injection..............0002) ce eee 290.9 228.3 | 0.78 
During Ro seeisiefa vidas dgphovar dee ie Se 0.199 325.2 214.6 0.66 
After OO Uadhee teen are 0 Sete || Rare ieads 299.4 230.9 0.78 
Animal III, weight 1.82 kgs. 
Before injection............0...06) se eee 305.3 | 243.4] 0.79 
During “8 acids esis sw nesedcsince 6 0.206 | 330.9 | 238.0} 0.72 
After EE bles baud mlaihareleroalal |) inactiaxe 306.6 235.3 0.77 
Animal IV, weight 1.47 kgs.: 
Before injection s.opd<atisse: os aiteug esters) Mesos 278.9 201.0 | 0.72 
During “Loe. sea :.| 0.186 | 297.6 | 197.9] 0.68 
After OES reper Bupteeehe eee ds sone! ayawe 278.1 205 .2 0.7 
In place of an increase of 60 to 100 per cent. in the respiratory 
exchange under the influence of the sodium butyrate, there was an 
increase of only 7 to 8 per cent. in the oxygen and none at all in the 
carbon dioxide. It is evident, therefore, that the loss of fat from 
the body must have been largely diminished, the butyric acid serv- 
ing as a source of energy in its place. A stimulating effect upon 
