28 DIGESTION AND FOOD. 



But the oxygen and hydrogen, which form water, may be 

 useful in the system in ways demanding their separation. In 

 the rapid strides made in organic chemistry within the last 

 few years, ample illustrations have been discovered of this 

 remarkable fact. When simply coming in contact with car- 

 bonic acid, which is always present in the system, the most 

 remarkable compounds are produced. Starchy and saccharine 

 principles, out of which animal fat may be formed, contain 

 only elements met with in carbonic acid and water. The 

 following table proves this : 



Stance formed. **%" f ,SS2j 



Name. Formula.. in eqs. in eqs. in eqs. 



Cellulose . . C 12 H 10 10 12 10 24 

 Starch . . C 12 H 10 OK> 12 10 24 



Cane Sugar , . C 12 H n On 12 11 24 

 Gum . . Cu HU O n 12 11 24 



Grape Sugar, dry . C 12 H 12 12 12 12 24 

 Grape Sugar, crystals d 2 H 14 14 12 14 24 



As Gregory says, this important group contains, in every 

 instance, hydrogen and oxygen in the proportion to form 

 water, so that the whole of the oxygen of the carbonic acid, 

 but not that of the water, has been separated. They may be 

 viewed theoretically as formed of carbon plus water; thus 

 starch may be C 12 + 10 HO. 



Water, as an alimentary principle, is found taken into the 

 system either alone or charged with organic and inorganic 

 constituents, or in combination with articles of food. Some 

 people think there are animals that need not and should never 

 drink, such as the rabbit, the sheep-, and even the kangaroo. 

 But this mistaken popular notion has arisen from these 

 animals deriving enough water for their purposes from a suc- 

 culent vegetable diet. Peed the rabbit on dry bran, and he 

 will like a little water. Place the sheep in the desert, and it 



