198 CTTAriER 21. 



Ulceration is also an occasional sequel of inflammation. When, either 

 by the violence of acute inflammation or by the more gi-adual effect of 

 chronic inflammation, the nutriment, which ought to be supplied to a 

 part by the free and constant flow of fresh blood through it, is arrested, — 

 the tone and vitality of the part is lowered, and it is then in a state on 

 which ulceration is likely to supervene. 



Ulceration may, however, occur almost without inflammation if the 

 vitality of the part is suflficiently lowered, as in cases of ulcerated heels 

 arising from horses being exposed to wet and cold. In other cases ulce- 

 ration is found as a result of a previously existing sore becoming indolent 

 or unhealthy. An ordinary sore for instance forms, and from, various 

 causes it may become indolent, and in time the tissues affected lose to a 

 greater or less degree their tone and vital power, and ulceration may 

 follow as a result in the manner described above. 



All tissues are liable to ulceration, but blood-vessels and nerves are 

 not so subject to it as other structures. Hence they can often be seen 

 permeating an ulcerating tissue. 



403, Process of Ulceration. 



Ulceration always commences at the surface of the diseased part, or in 

 other words, at the most extreme point of the capillary vessels. Here 

 of course the vitality is least, and therefore that part is the first to get 

 into that low state on which ulceration is likely to supervene. 



When the ulcerative process is about to manifest itseK on a mucous 

 membrane, there will be observed a red point or two and a few small 

 vesicles on the surface of the part, from under which a watery fluid, or in 

 some cases a thick grey slimy lymph exudes. The ulcerative process has 

 now fairly set in. Particle after particle of the tissue, as each becomes 

 dead, is removed as described above. Each fresh removal adds to the 

 size of the ulcer. As the sore becomes larger, its edges will appear more 

 ragged looking and swollen, and not unfrequently a fungoid kind of 

 flesh will rapidly arise from the sides and bottom of the cavity. The 

 appearance of any such growth is a very unfavorable sign. 



404. Varieties of Ulcers. 



Ulcers, according to the form they take, are described as fistulous, 

 phagedenic, and sloughing. 



Fistulous ulcers are those which run deep in various directions, eating 

 their way through and under the suiTounding tissues in long narrow 

 channels or fistulae. Phagedenic or spreading ulcers present to view a 

 round shallow cavity with ragged edges and a disposition to spread super- 

 ficially. Sloughing ulcers are those in which considerable portions of 

 the tissues come away at one time in flakes. 



Ulcers are also classed as healthy, inflamed, weak, or indolent. A 

 healthy ulcer has smooth edges, and a circular or oval surface studded 

 with florid granulations secreting healthy pus. Such ulcers are prone to 



