498 PRINCIPLES OF VETERINARY SURGERY 



bles the tubercle or the folhcle of Koster. "The histological 

 lesions of the actinomycostic nodule and the tuberculous 

 tubercle are alike. The invading parasite alone is different." 



The actinomjcostic nodule is primarily composed of 

 parasites surrounded by giant cells around which are found 

 accumulations of epithelioidal cells. When the process is 

 very rapid the nodule has all the characters of Virchow's 

 lymphoid tubercle, but it does not undergo caseous degen- 

 eration like the so-called tubercle. In time it undergoes 

 fatty or puriform degeneration, or else is transformed into 

 cicatricial tissue. 



The first sign of degeneration is marked by leucocytic 

 infiltration of the epithelioidal cells. The white cells dislo- 

 cate the parasites of the neoplasm and cause degeneration 

 or purulent exudation. Degenerated epithelial cells are 

 therefore found in actinomycostic pus, in addition to capitula 

 of dead actinomyces, hyaline bodies resulting from breaking 

 up of the clubs, pus cells and free grains of chromatin. The 

 infiltration of the actinomycostic neoplasm by polynuclear 

 leucocytes is therefore the first step in the degeneration of 

 the nodule, and is not a part of its normal constitution. These 

 data on the constitution of the actinomycostic neoplasm have 

 been elucidated by the investigations of Johne and Moor- 

 brugger, and were completed by the studies of Pawlowsky, 

 Maksutoff and Hoche. These writers have, in fact, demon- 

 strated that the penetration of the parasite into the tissues 

 is immediately followed by an organic reaction that aims to 

 surround and destroy it. The phagocytes, by reason of their 

 chemiotactic property, surround the fungus and undertake 

 its dislodgment. They carry off the filaments which develop 

 slowly from within the parasite when it is not destroyed. 



If the tissues weaken, the fungus destroys the cells that 

 surround it, and gradually transgresses farther. If, on the 

 contrary, the tissues resist, the phagocytes grasp the para- 



