276 DISEASE IN WILD MAMMALS AND BIRDS 
arteries show a general arteritis. The picture varies somewhat in differ- 
ent arteries ranging from a simple thickening of the adventitia to a 
change involving all three layers. There is hyaline change in the media in 
many sections. Lumen is in all cases reduced and in some there is 
active intimal proliferation in excess of what would be expected in 
connection with the medial change. A few of the arteries have their 
lumen completely obliterated. 
This is meant to illustrate the picture of vascular 
disease in the kidney in the absence of satisfactory evi- 
dence that nephritis per se antedated or accompanied 
changes in the vessels. In such cases vascular disease 
dominates, renal parenchymatous damage being rela- 
tively inconspicuous. Two old carnivores, a paradoxure 
and a skunk, presented shrunken kidneys mth prominent 
wide-walled vessels but in these some definite evidence of 
old nephritis was at hand. 
In so far as the relation of senility to nephritis is con- 
cerned the data at hand are not conclusive. In many old 
animals some degree of fibrosis is present without the 
existence of truly destructive changes in the parenchyma. 
Plimmer of London ^vlites that there is increased nephri- 
tis in old age but from our material I would be inclined 
to put in that in many cases the nephritis was the reason 
for old age rather than that old age brought on a 
nephritis. However the exact length of life and of 
captivity is known in too few specimens to make a con- 
clusion justified. 
Ascending Nephritis. 
There is some difference of opinion as to the definition 
of the term ascending nephritis, a confusion arising partly 
from the intended meaning of the participial adjective, 
partly from the frequency mth which infections or 
obstructions of the urinary outlets antedate or accompany 
suppurative nephritis. Perhaps our records may help to 
straighten out this matter. 
Ascending nephritis means for our study an infection 
which passes from the pelvic surfaces of the pyramids 
