FKAGILITUS OSSIUM. 199 



be co-existent. The pedal bones, however, when chronically 

 inflamed, become absorbed at their inferior borders externally, 

 and undergo the change described within their substance. 

 New formations, as bone-spavins and ring-bones, when of 

 long standing, are also liable to take on this action, becoming 

 brittle and easily broken. 



OSTEO-SARCOMA. 



Spina ventosa, or, as it is called by Gamgee, " fibro-plastic 

 degeneration of bone," is a disease very rarely found, except in 

 horned cattle, affecting the lower jaws generally; but in one 

 case which came under my notice the upper jaw was the seat 

 of the disease.— (See Photo-lithograph, Plate IV., Fig. 7.) These 

 tumours consist of an osseous crust, forming the walls of a cavity, 

 divided into several compartments containing a reddish fluid 

 tubercular material, or inspissated pus mixed with pieces of bony 

 or cartilaginous substance, bounded, as it were, by cyst-like 

 walls. These three conditions were all present in the case illus- 

 trated, and serve to form three definite stages of the disease: — 

 1st. The formation of a cyst containing a jelly-like fluid; 2d. 

 The transformation of this fluid into a grey caseous material, 

 which, when microscopically examined, presented a merely 

 granular appearance ; and M. The softening of the tubercular 

 matter into a semi-fluid, pus-like substance, mixed with pieces 

 of cartilage and bone. 



The cause of this disease has been attributed to external 

 violence ; but I have great reason to doubt the accuracy of such 

 a conclusion, and I am of opinion that the causes are intrinsic, 

 and due to the scrofulous diathesis. It occurs in young animals 

 mostly, and is said to affect steers more than bulls, its seat 

 being the neighbourhood of the second and third molar teeth, 

 where at first a small circumscribed swelling occurs. When 

 felt, the tumour is found to be hot, and that pressure causes 

 some pain to the animal. At first the animal experiences no 

 inconvenience ; indeed, it seems to suffer but little throughout 

 the various stages of the disease, provided the teeih do not 

 become carious, when of course the sufferings of the animal 

 will be severe, and it will lose flesh from inability to feed. 

 The bullock from which the drawing was obtained was quite fat, 



