230 PHYSIOLOGY AT THE FARM. 



tilage and the fibrous tissue, so as to partake of the qualities 

 of both. The examples are 1, Interarticular fibre-cartilages, 

 as in the joint of the lower jaw, in that of the clavicle in man, 

 in the knee-joint ; 2, The articular cavities of bones are often 

 deepened by a rim or border of fibro-cartilage, as in the hip- 

 joint ; 3, The connecting substance in the symphysis pubis 

 and between the bodies of the vertebne ; 4, The lining of the 

 bony grooves in which the tendons of muscles glide ; 5, 

 Nodules of fibro-cartilage in the substance of tendons, as in 

 the tendon of the tibialis posticus ; 6, The fibro-cartilage in 

 the orifices of the heart giving attachment to muscular fibres. 



Like fibrous tissue, fibro-cartilage yields gelatine by boiling 

 in water. 



Bone or Osseous Tissue. Bones are covered with a fibrous 

 membrane, termed periosteum, and contain marrow within, 

 which, particularly- in the long bones, fills their cavity and 

 renders them lighter. Bones consist of animal and earthy 

 matters ; the earthy constituent amounting to about two- 

 thirds of the weight of the bone. When bones are subjected 

 to a destructive heat, the animal matter is dissipated and the 

 earthy matter remains. If a bone be steeped in dilute nitric 

 or hydrochloric acid, the earthy matters are removed, and a 

 tough flexible substance remains, preserving in every part the 

 exact shape of the original bone. This tough residue is, by 

 boiling in water, resolved almost wholly into gelatine. It is 

 therefore improperly called the cartilage of bone. The earthy 

 constituents of bone consist principally of phosphate of lime, 

 with about a fifth part of carbonate of lime, and much smaller 

 proportions of fluoride of calcium, chloride of sodium, and salts 

 of magnesia. 



The following is the analysis of Berzelius, placed side by 

 side with a recent analysis by Mr Middleton of University 

 College, London. In 100 parts are 



