OSTEOLOGY 21 



Flat Bones. — The flat bones occur where extensive protection 

 is needed, as in the cranial region; or where large surface for muscular 

 attachments is needed, as in the costal and pelvic regions. Flat 

 bones are made up of two thin layers of conipact bone with a vari- 

 able amount of cancellous tissue interposed. 



Irregular Bones.— Th.& irregular bones include . the vertebrae, 

 the patellae, and the carpal bones. 



Compositioii of Bone. — ^Bone consists of organic and inorganic 

 matter. Organic matter gives toughness and elasticity to the bone, 

 and inorganic matter hardness. The organic substance of bone is 

 called ossein. When boiled in water ossein is resolved into gelatin. 

 The following tables^ give the results of an analysis of the femur, 

 fresh, of a mature hen. 



Fresh femur: 



Water i8. 23 per cent. 



Dry matter 81 . 77 per cent. 



Dry matter: 



Organic matter 63 . 09 parts 



Inorganic matter 18.68 parts 



Salts in dry matter: 



Calcium 6.970 per cent. 



Magnesium o. 283 per cent. 



Potassium. 0.004 per cent. 



Sodium o. 276 per cent. 



Iron 0.020 per cent. 



Phosphorus 3.210 per cent. 



Sulphur 0.08s P6r cent. 



Chlorine o. 520 per cent. 



Carbon diozid o-SS" per cent. 



The inorganic matter of the femur of the hen consists of 18.68 

 parts or 22.84 per cent, of dry matter, and the organic matter of 

 77.16 per cent. Stated in other words the femur, including its 

 contained marrow, consists of organic and inorganic matter in the 

 ratio of 3.4, approximately, to i. 



The Skeleton of the Fowl, — The skeleton of a bird is remarkable 

 for the rapidity of its ossification. It is worthy of note that other 

 parts of the bodies of adult birds also become ossified. Among such 

 parts are the tendons of the muscles of the legs, of the feet, and of 'the 



1 Greatful acknowledgment is hereby made to Dan M. McCarty, Chemist, 

 Animalilndustry Division, North Carolina Agricultural Experiment Station, for 

 this analysis. 



