192 THE DISEASES OF DOMESTIC ANIMALS. 



The genesis of these cells in the nasal discharge was pretty cor- 

 rectly given by Gerlach, but since his day we have been taught that 

 the greater portion of them are migrated leucocytes ; this is true for 

 pus-formation, but in inflammations it is certain that proliferation 

 also takes place — hence some of our round cells may be prolifer- 

 ated, epithelial, or connective-tissue elements. This question of the 

 origin of spindle-cells by formative processes or inflammations is 

 still an open one, to my mind, notwithstanding the authority of 

 Cohnheim. I, for one, do not believe a white blood-cell can trans- 

 form or develop into a spindle-cell. "We can not tell the difference 

 between a white blood-cell and the intermediate or round cell con- 

 dition of the developing spindle-cell. 



Like begets like, and in inflammations, where formation takes 

 place, it is my opinion that the migrated cells perish by fatty de- 

 generation, and the formation is due, as long ago asserted by Vir- 

 chow, to the permanent elements. 



In glanders we have more or less circumscribed forms of neo- 

 plastic formations. The first of these are the tubercles, which vary 

 in size from submiliary to that of a cherry or acorn ; 2. The gland- 

 ers-growths, varying from the above to the size of an apple, but of 

 irregular form ; 3. The glanders-infiltrations, which are less circum- 

 scribed in their outlines, and extended along the surface ; these are 

 particularly to be found in the nasal mucosa and sub-cutis. 



The Glanders-Tubercle. — There has been and still exists much 

 discussion and difference of opinion as to what should be considered 

 a true tubercle. 



While this discussion is valuable, from an anatomical and prac- 

 tical sense, it has still led to much unnecessary mystification among 

 students. 



It has always been the old hunt after specific cells, or specific 

 characteristics, by which to decide between two (macroscopically) 

 apparently similar objects. In the energy of this hunt the true spe- 

 cific has been lost sight of to a much too great degree. 



The cause, irritans, is the specific element ; the product may or 

 may not have specific characteristics. We find tubercles occurring 

 under a great variety of circumstances and among many different 

 species of animals. Different causes lead to their production in 

 one and the same species. 



In the horse, tubercles occur in glanders ; an idiopathic miliary 

 tuberculosis has been reported, however. 



I can not at present tell whether there are any marked structural 

 differences in these tubercles in the horse. 



