PRINCIPLES OF VETERINARY SURGERY 655 



tissue by a fibrous neoformation, having absolutely the same 

 microscopic physiognomy as the tumor of the nasal cavities. 



A hurried microscopic study of the disease made by Pro- 

 fessor Mathis some years ago has shown that the diseased 

 bones are composed chiefly of fibrous tissue harboring in its 

 midst lamellje, splinters and tracts of osseous or cartilagi- 

 nous substances which cross on6 another. Recent investiga- 

 tions have proven that the lesion from a histological point of 

 view is similar to that of rhinoscleroma of man, with the ex- 

 ception that Mickulicz's cells, which have been regarded as 

 the specific elements, are wanting. As this feature is, how- 

 ever, not absolutely characteristic, it remains to be seen 

 how much importance to attach to it. Mickulicz himself 

 has stated that too much importance must not be attached 

 to the elements bearing his name. The characteristic mi- 

 crobian agents of the disease can not be detected in sections 

 of the tumor, but in view of their form in the lesions this cir- 

 cumstance is not astonishing. 



Returning to the original-question it may be said that the 

 tumors are almost always exclusively fibrous, consisting of 

 adult tissue meagerly supplied with cellular elements in the 

 deep layers and new tissue rich in active elements at the 

 periphery, and in certain regions related to fibrous bands 

 that seem to emanate from the remains of thei periosteum. 

 The neoplasm is surrounded by a layer of new fibrous tissue 

 in the course of active proliferation, and at certain points on 

 its inner aspect may be found cartilaginous centers the 

 fundamental substance of which does not stain at all, or 

 stains badly, and its cellular elements appear to be surround- 

 ed with a rather conspicuous capsule. The peripheric fibrous 

 layer, probably of periosteal origin, sends extensions into the 

 neoplasm that divide it into compartments. These second- 

 ary septa again send projections into the depth of the tumor, 

 which are the seat of an active proliferation. 



