OF VETERINARY MEDICINE. 235 



but leave out corn and everything that tends to fat. In puppies 

 change the food ; give boiled meat with oatmeal, make a strong 

 stew of it. If the legs in the foal do not get strong, apply 

 splints and bandages. Lime water is good for rickets. Cod 

 liver oil is good for puppies. 



HEALING OF BOXE r REPAIR). 



When a bone breaks, either completely or incompletely, there 

 results more or less hemorrhage; the surrounding tissues are 

 torn and infiltrated with blood ; a moderate degree of inflam- 

 matory exudation and cellular migration takes place, but in the 

 absence of infection the inflammation subsides after a few days, 

 soon to be followed by regeneration. As early as the second day 

 the cells of the periosteum begin to grow and proliferate and 

 show many karyokinetic figures. In two or three days a vascular 

 formative tissue has developed which is rapidly developed and 

 differentiated into osteoid and chondroid tissue. This formative 

 tissue produced by the peristeum is known as the external callus ; 

 that which extends in between the fragments is known as the 

 intermediary callus. The tissue regenerating from the medulla 

 is called the myelogenic callus. 



The periosteal callus extends around the fragments like a 

 capsule for some little distance on each side of the break. At 

 the end of the 'first week the inner layers of the newly formed 

 tissue have become differentiated into osteoid tissue and hyaline 

 cartilage especially so in young and in animals like the dog, and 

 then calcification sets in and porous bone develops — the bony 

 callus. During the succeeding two or three weeks the amount 

 of bony callus constantly increases. 



The myelogenic callus is formed by the proliferation of the 

 osteoblasts; it is not of so much importance as the periosteal 

 callus. At about the end of the seventh week the periosteal 

 callus is totally ossified, consisting of a porous, rather soft, os- 

 seous tissue, which gradually becomes substituted by new bone 

 of considerable density by means of lacunar resorption and the 

 formation of medullary spaces on the one hand (osteoclasts 

 break down bone) and the production of new lamellae or growth 



