436 BENIGN TUMOURS. 



increase on one side of the fang only, unless the opposite side 

 has been exposed by the absorption of the gum, or deprived of 

 its periosteal covering. In some cases nodules of cementum are 

 found in various parts of the fang, even near the neck of the 

 tooth." And he concludes that " dental exostosis is caused by 

 that condition of the periosteum which is called irritation — a 

 state usually induced by pre-existing disease in other dental 

 tissues, and in a great majority of cases by caries — not always, 

 however." — {Dental Physiology and Surgery, by John Tomes, 

 Surgeon-Dentist to the Middlesex Hospital.) 



VII. — CALCAREOUS TUMOURS. 



These consist of a deposit of calcareous salts in various parts 

 of the body — in the testicle, parenchyma of organs, upon nerves, 

 &c. 



I have seen a concretion of this kind in the substance of 

 the liver, causing fatal haemorrhage by forcing its way through 

 Glisson's capsule. 



VIII. — OSSEOUS TUTMOURS AND OSTEOPHYTES 



Are very irregular, of a warty stalactic shape, and are common 

 in the neighbourhood of joints where the articular surface is 

 affected with caries, and sometimes surround the tendons of a 

 limb when no joint disease is present. — (See Photo-lithograph, 

 Plate I., Fig. 4.) 



They result from the ossification of an exudate which has 

 been formed in consequence of some cause of inflammation. 

 Osseous tumours are of a more compact structure than osteo- 

 phytes, and grow more from the compact structure of the bone 

 itself Cases of great lameness sometimes occur from these new 

 formations becoming inflamed from accidental causes, and I 

 have seen necrosis of them produce sloughing of the skin, and 

 the formation of sinuses. 



IX. — OSTEOID TUMOURS — OSTEO-SARCOMA. 



(See Photo-lithograph, Plate I., Pig. 9.) 



These are tumours of irregularly protuberant surface, affect- 

 ing both the upper and lower jaws of horned cattle. They are 



