PRINCIPLES OF VETERINARY SURGERY 415 



phonse Guerin, in the treatment of surgical accidents by 

 sheltering them from the air, neatly demonstrated the mias- 

 matic nature of purulent infection. The study of anthrax 

 singularly facilitated the study of this disease. Various mi- 

 cro-organisms were found in pus, and the explanation of 

 their action soon followed. The septic agents penetrate into 

 the blood vessels through abrasions in the capillaries of the 

 granulation tissue, or through larger vessels, or possibly 

 gain the endovein by causing inflammation of the vessel. 



A broken vessel is rarely ever the entrance point of puru- 

 lent infection. Generally pyaemia x'esults because the agents 

 cause local, multiple phlebitis. In veterinary pathology pur- 

 ulent infection is at other times frequently the result of 

 phlebitis of the jugular vein. Irritated by the septic agents, 

 the walls of the veins become successively inflamed; the 

 vascular endothelium becomes wrinkled and gathers an in- 

 fected thrombus little by little. From this clot emboli break 

 away and are carried into the right side of the heart, and 

 then immediately to the capillaries of the lungs, where their 

 considerable dimension opposes their onward course. Ar- 

 rested at this point they provoke obstruction and local mor- 

 tification that becomes the center for the formation of an 

 abscess. 



WherT the emboli are of small dimensions, or when the 

 septic agents are launched into the general circulation 

 through the medium of the leucocytes, the small dimension 

 of these elements permits them to pass through the network 

 of pulmonary capillaries to colonize elsewhere, — in the paren- 

 chymatous organs, the kidneys, the brain, the muscles, etc. 

 It causes alterations that are more particularly formidable 

 in organs that are already diseased or have been previously 

 injured. The firing of horses affected with or approaching 

 an attack of strangles is nearly always followed by the ap- 

 pearance of an abscess at the seat of the cauterization. The 



