LIME PHOSPHATE. 



45 



Fig. 1. 



much over the animal matter, and is present in greater abundance there 

 than in any other part of the frame. In the dentine, a softer tissue, it 

 is in somewhat smaller quantity, and in the bones smaller still ; though 

 in the bones it continues to form more than one-half the entire mass 

 of the osseous tissue. The importance of this substance, in com- 

 municating to bones their natural stiffness and consistency, may be 

 readily shown by the alteration which they suffer from its removal. If 

 a long bone be macerated in dilute muriatic acid, the 

 earthy salt, as already mentioned, is dissolved out, 

 after which the bone loses its rigidity, and may be 

 bent or twisted in any direction without breaking. 



(Fig. 1.) 



In the formation of the bony skeleton, during foetal 

 life, infancy, and childhood, the cartilaginous sub- 

 stance previously existing is replaced by osseous 

 matter, which contains a larger proportion of calcare- 

 ous salts ; while the anatomical texture of the parts is 

 also changed, giving rise to the characteristic forms 

 of bony tissue. This progressive consolidation of the 

 framework of the body is known as the process of 

 "ossification." In some instances this process is 

 defective, owing to partial failure in the powers of 

 assimilation; and as the rigidity of the skeleton, ac- 

 cordingly, does not increase as it should do in propor- 

 tion to the weight of the body and to muscular action, 

 the bones become gradually bent and deformed, some- 

 times to an extraordinary degree. This affection has 

 received the name of Rachitis. 



A somewhat similar result is produced by a morbid 

 softening of the bones, which sometimes comes on in 

 adult life, known as Osteomalakia. In this disease 

 the bony fabric, after its formation, becomes altered 

 in texture and composition ; and, the new substance which takes its 

 place being deficient in calcareous matter, a progressive yielding and 

 deformity of the skeleton takes place, like that which happens in cases 

 of rachitis. 



In the plasma of the blood the lime phosphate, though insoluble in 

 simple alkaline watery liquids, is held in solution by its union with the 

 albuminous ingredients. It has been shown by Fokker that the earthy 

 phosphates added to white of egg unite with the albuminous matter and 

 become soluble in considerable proportion. This explains the presence 

 of lime phosphate in a liquid form both in the blood and in the milk, 

 both fluids which have an alkaline reaction. In the urine, on the other 

 hand, it is held in solution by the presence of the acid sodium biphos- 

 phate. Accordingly, whenever the urine is rendered alkaline by the 

 addition of soda or potassa, the earthy phosphates are precipitated in 

 the form of a white turbidity. 



FIBULA TIED 

 IN A KNOT, after 

 maceration in a di- 

 lute acid. (From a 

 specimen in the mu- 

 seum of the College 

 of Physicians and 

 Surgeons.) 



