94 FORMATION OF FAT. 



This excess of carbon, as it cannot be employed to 

 form a part of any organ, is deposited in the cellular 

 tissue in the form of tallow or oil. 



At every period of animal life, when there occurs 

 a disproportion between the carbon of the food and 

 the inspired oxygen, the latter being deficient, fat 

 must be formed. Oxygen separates from existing 

 compounds, and this oxygen is given out as carbonic 

 acid or water. The heat generated in the formation 

 of these two products contributes to keep up the 

 temperature of the body. 



Every pound of carbon which obtains the oxy- 

 gen necessary to convert it into carbonic acid from 

 substances which thereby pass into fat, must dis- 

 engage as much heat as would raise the tempera- 

 ture of 200 lbs. of water by 70°,— that is, from 32' 

 to 102°. 



Thus, in the formation of fat, the vital force pos- 

 sesses a means of counteracting a deficiency in the 

 supply of oxygen, and consequently in that of the 

 heat indispensable for the vital process. 



Experience teaches us that in poultry, the maxi- 

 mum of fat is obtained bv tyino- the feet, and bv a 

 medium temperature. These animals in such cir- 

 cumstances may be compared to a plant possessing 

 in the highest degree the power of converting all 

 food into parts of its own structure. The excess of 

 the constituents of blood forms flesh and other 

 organised tissues, while that of starch, sugar, Sec, 



