ARTERITIS. 579 



common iliac, but the aorta post, divides into internal and 

 external iliacs). This plug was firmly adherent to the roof of 

 the artery; that is, to that part lying in contact with the 

 vertebrae. It w^as not sufficiently large to obstruct the stream 

 of blood completely, but it must have caused a material lessening 

 of the stream. The internal iliacs, however, were completely 

 plugged up, and the outside of the fibrinous clot was adherent 

 to their walls — in many places all the way round. In one 

 place especially, a calcifying process is taking place in the 

 coagulum. If such things are not already too familiar to you, 

 I wish you would look in at Clyde Street any day before two 

 P.M., for the condition is to me somewhat new. — Yours very 

 truly, John Barlow." 



In all the instances recorded of arteritis in the horse, the 

 disease w^as of a chronic and limited character, invading a por- 

 tion, more or less in extent, of one, or at most two, large arteries 

 and their branches. The diffuse suppurative arteritis described 

 by writers upon human surgery, so far as my knowledge extends, 

 is quite unknown. Arteritis is generally caused by an injury, 

 though such may not generally be traceable. The iliac arteries, 

 and more especially their branches, are imbedded in very powerful 

 muscles, and during the violent contractions of those muscles 

 are liable to be injured, the result of the injury being inflam- 

 mation ; exudation from the walls of the vessel, forming the 

 nucleus of a clot ; the clot being, as in phlebitis, composed of 

 lymph exuded from the walls of the vessel, and of coagulated 

 blood. The formation of the coagulum always begins at some 

 definite fixed spot, and points to some source of local irritation ; 

 Irom this it extends until the artery is plugged up to its origin 

 from the parent trunk. 



The symptoms of plugging of the external iliacs are coldness 

 of the extremity, with muscular debility, which increases wdth 

 exercise, and atrophy of them ; and should the arteries of both 

 sides be plugged, the symptoms simulate those of paraplegia. The 

 diagnostic sign, however, is absence of pulsation in the artery, 

 detectable by examination per rectum. The loss of blood 

 supply to the extremity furnished ly these arteries is not 

 sufficient to cause gangrene ; a modified circulation being 

 maintained by branches of other arteries, which anastomose 



