426 ORGANIC CHEMISTRY. 



medium for its conveyance through the body. As 

 a consequence of the changed color of the globules, 

 arterial blood is of a bright scarlet, while venous 

 blood is dark red. The same change of color which 

 takes place in the lungs, may be readily produced by 

 agitating blood drawn from the veins with air or ox- 

 ygen gas. 



What is said 1059. RELATIONS OF FOOD AND TEM- 

 of therein- PERATURE. In proportion as the draft of 



tions of food . . n . 



and tempera- & furnace is increased, more fuel must be 

 tore? supplied for its combustion. For the same 



reason more respiratory food must be taken into the 

 system, in proportion as more atmospheric oxygen is 

 inhaled. The fact that a larger quantity is required in 

 northern climates thus receives a scientific explanation. 

 The preference entertained in arctic regions for cer- 

 tain kinds of food, is also accounted for by the same 

 necessity for increased resistance to the external cold. 

 The train oil and fat which the Greenlander con- 

 sumes with avidity, are a better fuel in the animal 

 body than the starch which form a principal part of 

 the food consumed in warmer climates. The chemical 

 reason of this difference is found in the fact, that 

 starch and allied substances contains oxygen in larger 

 proportion. They are, as it were, in their natural con- 

 dition, partially burned or oxidized substances. 



1060. CHANGE OF THE ANIMAL TISSUES. 



What change 



takes place in In proportion to the muscular or nervous 



lhlbodyT f activity of the animal, the substance of 



the body is disorganized and returned to 



the blood from which it was produced. From the 



