BONE 



175 



bone formation. The long bones are preformed in cartilage into 

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

 undergo calcification. All bone is developed from fibrous tissue. 

 The cartilage merely plays the part of scaffolding and is all 

 replaced by fibrous tissue before ossification takes place. 



TABLE XXVIII. 



RELATIVE STRENGTH OF THE LONG BONES. 

 (MAN AGED 31.) 



* Torsion applied to the extremity of the bone with a leverage of 16 cm. produced 

 a spiral fracture 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 will 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 

 proteoses and peptones. Now, experiment has shown that calcium 

 salts dispersed in an albuminous hydrogel are thrown out of 

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

 calcium phosphate is much more insoluble in proteose-peptone 

 solution than the carbonate, which is only slightly affected by the 



