CHAPTER IX 

 THE ANIMAL BODY. 



The elements found in animal tissue are the same as those 

 found in the plant world, and while sodium and chlorine are con- 

 sidered by some as non-essential for plant development, in the 

 formation of the animal's tissue they are indispensable. Fluor- 

 ine and silicon are also always found in the animal body, but 

 are not known to be absolutely essential for life or growth. 

 Fluorine occurs in small quantities in the teeth and bones, and 

 silicon in the hair, wool and feathers. 



The compounds forming the animal body are many and very 

 complex and only a brief survey of the principal ones can be 

 given here. 



The constituents of the animal body may be divided into: 



(1) Inorganic compounds, including water, various acids and 

 numerous salts ; some are in the solid state, as the calcium phos- 

 phate of the bone Bothers are in solution as the sodium chloride 

 of the blood. 

 (2) Organic compounds, 



Of the inorganic constituents, by far the largest part is con- 

 tained in the bones. In fat animals 75 to 85 per cent of the 

 ash constituents of the body are found in the bones. Bono 



