THE HORSE. 193 



Again, a peculiar chronic production in old horses, with more or 

 less bronchial catarrh, is known as " bronchitis nodosa"; this has 

 been mistaken for •jjlanders and for true tuberculosis. The nodes are 

 mostly conjposed of connective tissue, with round cells between the 

 fibers, and consist of a circumscribed proliferation of the walls of 

 the finest bronchioli, as they lose themselves in the infundibula. 

 At times one can make a differential diagnosis, macroscopically, with 

 ease, a transvei-se section of the object revealing the lumen of the 

 air-tube. Carefully executed microscopic section will ahcays reveal 

 the true nature of these nodes. 



Hereditary influences do not ai)pear to play any part in the pro- 

 duction of tuberculosis in the hoi^se. 



The ylamhrs-tiibercle^ in the lungs^ is of a permanent character ; 

 it does not extend, as in human tuberculosis, by infection of the 

 neighboring tissues, forming large masses of degenerating material, 

 which break down and lead to the formation of cavities — one form 

 of phthisis pulmonuni. They do not occur in any such quantity 

 as in the human lung. They are inclined to calcify, although fatty 

 degeneration of their centers is by no means uncommon. 



They are due to a specific cause, the irritans of glanders. 



I have no doubt that miliary tuberculosis can be produced In the 

 horse, by the entrance of foreign substances into the lungs, as the 

 aspiration of a spray containing in it the sputa from human phthisi- 

 cal subjects, as has been done in dogs. 



"We know nothing of the cause of the very rare miliary tubercu- 

 losis in the horse. 



In men and cattle wc have an hereditary predisposition to tuhcr- 

 culosis. 



Here comes the ridiculous part of the assertion of many authors. 



The diseases are identical. Why ? Because in both cases giant- 

 cells are found in the tubercles. The tubercles of glanders ai*e not 

 true tubercles. 



1. Because they have no giant-cells. 



2. Because they have a central vessel, which these others do not. 

 Both forms have a vascular circle, or retc, cmbracinji: them. 

 Giant-cells are not specific to tubercles. They are not present in 



all stages of the development of the neoplasm. According to Kol- 

 likcr, their presence is always indicative of retrogressive or destruc- 

 tive protissi's ; they arc the rodents of cellular pathology, or physi- 

 ology. 



They occur in the medulla of the bones, in sarcomatous tu- 

 mors, and, according to Kolliker, are one of the active causes of 



13 



