DISEASES OF THE BLOOD VESSELS 69 
essential alterations are inflammatory and degenerative, 
of which the latter are by all odds the more important. 
The former are either involvements of the vessel walls 
by frankly infectious processes, or less easily proved to 
be bacterial in origin, as is the case with periarteritis 
nodosa. Acute arteritis and phlebitis are constantly 
encountered and present nothing unusual. General nodal 
periarteritis has been seen in the lower animals, Lupke 
having reported (1) before the German Pathological 
Society a big outbreak in cows, but it is less common than 
among men ; we have not discovered it here. 
Thromboses. 
Thrombosis is practically always a parasitic or an 
infectious process although at times considerable diflS.- 
culty is encountered in explaining the source of the 
worms or bacteria. Thus, for example, the iliac or femoral 
thromboses which are at the bottom of intermittent 
claudication, are frequently quite vague in origin. We 
have had one such case in a deer in which a partly occlud- 
ing thrombangeitis existed in both femoral arteries and 
veins. Mesenteric thrombosis, a serious condition in 
cattle and horses from infestation with sclerostomum or 
strongylus, has not been proven at the Garden, but we 
have seen one case of numerous thromboses of the venous 
radicals in the jejunal wall apparently due to some nema- 
tode larvas; the specimens were so soft by decomposition 
that determination was not attempted. There occurred 
a thrombosis of the cava and aorta originating from a 
necrotizing cloacitis, apparently streptococcal in nature, 
in a Demoiselle crane. The clot, while not totally occlu- 
sive, extended nearly as far as the heart in the vein and 
the abdominal aorta. There is also on record a throm- 
bosis of the vena cava and right pulmonary vein in an 
American beaver, harboring Hepaticola hepatica in the 
liver, with a fibrosing pneumonia due to this parasite. 
(1) Verh. deutsch Path. Oesel., 1906, X, 149. 
