Anatomical Changes. 695 



neetive tissue. That from such connective tissue new formations can actually 

 develop without the previous existence of lesions has been confirmed by Hahn by 

 the demonstration of an intact mucous epithelium on their surface and by Babe, 

 who demonstrated the presence of the normal elastic basement membrane of the 

 mucosa on the surface of the cicatrix. 



In the trachea the ahove-descrihed lesions usually occur 

 on the ventral wall, in the larynx usually on the arytenoid 

 cartilages, the lateral ventricle and epiglottis. In grave cases 

 the trachea may be studded with its entire course with thickly 

 strewn nodules, ulcers and cicatrices, the cartilages even being 

 exposed by some of the ulcers. 



In the nasal cavity only a few nodules or ulcers are found, 

 usually in the upper portions and on one side only, while the 

 lower portion of the mucous membrane suffers no changes ex- 

 cept catarrhal injection and tumefaction. In cases that are 

 less recent or are more acute in character the mucous mem- 

 brane of one or both nasal cavities may be so studded with 

 nodules and scars that it is almost impossible to find a healthy 

 area of tissue; old scars from former attacks may also be 

 found in the midst of acute lesions. In rarer instances the 

 ulceration may have extended to the cartilage of the septum 

 or the destructive process may have resulted in the perfora- 

 tion of the latter and formed one or more roundish holes. 

 Finally, in cases that are equally rare, when the inflammatory 

 process has extended to the periosteum of the neighboring 

 bones (maxillary, nasal and muscles) bosselated enlargements 

 and exostoses may occur on their surfaces. 



Disease of the sinuses is usually the result of an extension 

 of the morbid process from the nasal cavities. The antrum 

 of Highmore on the side of the affected nasal cavity is affected 

 most frequently, the frontal sinus coming next. Here also the 

 disease sometimes leads to the formation of nodes and ulcers, 

 although in most instances the surface of the mucous membrane 

 is smooth while its substance together with that of the sub- 

 mucous connective tissue forms an intensely yellow gelatinous 

 layer about 1-2 cm. in thickness, the corresponding sinus con- 

 taining much muco-purulent secretion. In rare cases cicatrices 

 are found here also, or the mucous membrane is simply 

 thickened, tough and bosselated on the surface. Similar morbid 

 changes are occasionally found also in the guttural pouches and 

 the Eustachian tubes. 



The mucous membrane of the digestive tract is rarely 

 found affected. In exceptional instances lesions are met with 

 in the pharynx but only when the nasal cavities are likewise 

 involved; here, too, the lesions consist of gelatinous infiltration 

 of the mucous membrane and submucous connective tissue; 

 occasionally there may be ulceration, but cicatrization is not 

 the rule. Involvement of the intestine is still more rarely 

 observed. In several horses from a badly infected stable the 

 authors found the solitary follicles and Peyer's patches in the 



