DISEASES OF CATTLE 433 



are exposed. The skeleton of the adult ox is made up of the following 

 number of bones : 



Spinal column 45 



Head 28 



Chest 27 



Shoulder 2 1 on each side. 



Arm 2 1 on each side. 



Fore arm 4 2 on each side. 



Fore foot 40 20 on each side. 



Pelvis 2 1 on each side. 



Thigh 2 1 on each side. 



Leg 6 3 on each side. 



Hind foot 38 19 on each side. 



Total 196 



Without attempting to burden the reader with the technical 

 names and a scientific classification of each, it appears desirable to 

 describe some of the characteristics of forms in general, and of a few 

 classes into which they may be divided. In the early fetal life 

 the place of bone is supplied by temporary cartilage, which grad- 

 ually changes to bone. For convenience of study, bones may be said 

 to be composed of a dense form of connective tissue impregnated with 

 lime salts and contain two elementary constituents the organic, or 

 animal, and the inorganic, or earthy. In young animals the former 

 predominates; with increasing years the relative proportions of the 

 two change, so that when advanced age is reached the proportion of 

 inorganic far exceeds the organic. The gradual change with advanc- 

 ing years from organic to inorganic has the effect of rendering the 

 bone harder and more brittle, and though it is stronger the reparative 

 process is slower when injury does occur. 



The bones are nourished in two ways: First, from the outside 

 through their covering, called the periosteum the thin, strong mem- 

 brane that covers every part of the bone except the articular surface 

 of the joints and, second, from within through the minute 

 branches of blood vessels which pass into the bones through holes 

 (foramen) on their surface and are distributed in the soft structure 

 (medulla) of the inside. The structure of the bone is divided into 

 two parts the compact or hard material of the outside, which gives 

 strength and is more abundant in the shafts of long bones, and the 

 cancellated softer tissue of the inside, which affords accommodation 

 to the blood vessels necessary for the nourishment of that part of 

 the structure. 



In shape bones are divided into three classes long, flat, and 

 short. The long bones are the ribs and those mostly found in the 

 limbs; the flat bones are found in the head, the shoulder, and the 

 pelvis; and the short bones in the spinal column and in the lower 

 portions of the limbs. With this little introduction, which seems 

 almost indispensable, we will proceed at once to the consideration 

 of diseases of bones, for they undergo diseased processes like any 

 other living tissue. 



