THE DISEASES OF CATTLE. 24.9 



best kind of fodder. The inference is, that the digestive or ■ 

 gans are not in working condition ; therefore, in such cases, the 

 food operates as an exciting cause of disease. 



The effects of cheap and damaged food are too well known ; 

 poor food is dear at any price which may be asked for it ; it 

 may not furnish sufficient carbon ; if so, the animal is deprived 

 of the power of reproducing itself, and must eventually suffer 

 (see article on feeding). 



These preliminary remarks are introductory to the following 

 on diseases of the bones ; but before I allude to them I have a 

 few brief remarks to offer on the 



MECHANISM AND STRUCTURE OF BONES. 



Bones have many things in common with the soft tissues and 

 organs ; for example : arteries, veins, nerves, lymphatics, and 

 a connecting cellular web. Their structure, in the embryotic 

 state, is highly vascular, yielding, and gelatinous. They have, 

 externally, a fibrous investment known as periosteum, which is 

 well supplied with arteries, veins, nerves, and absorbents ; and it 

 is through the intervention of this fibrous tunic, that the vessels 

 proper to bones reach their ultimate destination. On the inte- 

 rior surface of hollow bones, we find a membrane of similar 

 structure, only more delicately organized. The cavity of the 

 shaft bones is usually occupied by a quantity of adipose matter, 

 known as marrow ; this is enclosed in laminated cells, and is 

 supposed to be a sort of aliment in reserve, to provide against 

 accidental emergencies of non-nutrition. 



COMPOSITION OF BONES. 



Bones consist of two constituents ; viz., animal basis and 

 calcareous matter. In the healthy adult, the proportions are 

 as follows : — 



Animal Matter, 33| per cent. 



Calcareous Matter, 66f " " 



100 



