BONE 



218 



processes of fibrous tissue find their way and they in turn underjjjo 

 calcification. All bone is developed from Jihrous tissue. The 

 cartilage merely plays the part of scalTolding and is all replaced by 

 fibrous tissue before ossification takes place. 



TABLE XXXII 

 Relative Strength of the Long Bonks 

 (Man aged 31) 



Torsion applied to the extremity of tlie bone with a leverage of 16 cm. produced a spiral fracturi; 

 with the forces given above. (Amar.) 



Practically nothing is known of the physical chemistry of bone 

 formation. Microscopic investigation suggests to our mind a 

 process similar to the formation of a honeycomb. The cells of 

 fibrous tissue detailed to build bone, i.e., osteoblasts, secrete 

 material containing a fair proportion of the phosphate and car- 

 bonate of calcium. It is known that the presence of a small 

 quantity of a colloidal complex alters the solubility of inorganic 

 matter. For example, calcium phosphate is more soluble in an 

 albuminous hydrogel than in water. This effect is even more 

 marked with calcium carbonate. If we presume the presence 

 of the salts of lime in the fibrous tissue cells, then, by the principle 

 of Willard Gibbs, they w^U be found in greatest concentration 

 where the surface tension is lowest, that is at the cell borders. 

 Another factor may be brought into play, viz., alterations in the 

 colloidal matrix. Albumin is broken down in the body to pro- 

 teoses and peptones. Now, experiment has shown that calcium 

 salts dispersed in an albimiinous hydrogel are throw'n out of 

 solution when protesoses and peptones appear in the gel. Further, 

 calcium phosphate is much more insoluble in proteose-peptone 

 solution than the carbonate, w'hich is only slightly affected by the 

 change. It is significant that bone ash contains about 84 per cent, 

 of the former and only 7-6 per cent, of the latter salt. 



