PHOSPHATE OF LIME. 



Parts per 1,000. 



In Urine (proportion to weight of ash, Fleitmann) 25'700 



" Excrements (Berzelius) 40'000 



" Bone (Lassaigne) 400- 



Vertebra of a rachitic patient (Bostock) 136' 



Teeth of Infant one day old. "1 C 510' 



Teeth of Adult I 610- 



Teeth, at eighty-one years., ^saigne^j 660 . 



Enamel of Teeth. . . 885- 



By this table it is seen that the phosphate of lime exists in 

 very small quantity in the fluids, but is abundant in the 

 solids. In the latter the quantity is in proportion to the 

 hardness of the structure, the quantity in enamel being, 

 for example, more than twice that in bone. The variations 

 in quantity with age are very considerable. In the teeth 

 of an infant one day old, Lassaigne found 510 parts per 

 1,000 ; in the teeth of an adult, 610 parts ; and in the teeth 

 of an old man of eighty-one years, 660 parts. This increase 

 in the calcareous elements of the bones, teeth, etc., in old age 

 is very marked ; and in extreme old age they are deposited in 

 considerable quantity in situations where there existed but a 

 small proportion in adult life. The system seems to grad- 

 ually lose the property of appropriating to itself organic mat- 

 ters ; and though articles of food are digested as well as ever, 

 the power of assimilation by the tissues is diminished. The 

 bones become brittle, and fractures, therefore, are common at 

 this period of life, when dislocations are almost unknown. 

 Inasmuch as the real efficiency of organs depends on organic 

 matters, the system actually wears out, and this progressive 

 change finally unfits the various parts for the performance of 

 their functions. An individual, if he escapes accidents and 

 dies, as we term it, of old age, passes away thus by a simple 

 wearing out of his organism. 



Function of Phosphate of Lime. This substance, as be- 

 fore remarked, enters largely into the constitution of the 

 solids of the bodv. In the bones its function is most appa- 



