THE URINARY TRACT 279 
where there was, judging from the protocol and histo- 
logical sections, obvious opportunity for its ascent, in ten 
other cases of cystitis and urethritis no pelvic or renal 
disease is recorded; two of these were acute exudative 
cystitis and one was a tumor. It seems that wild animals 
seldom live long enough to have obstructions exert back 
pressure of urine to the extent which one is accustomed 
to see in human medicine. Hydroureter and hydro- 
nephrosis have not been seen. 
Abscess of the kidney has occurred occasionally in the 
metastatic form and only twice as the large destructive 
process such as is seen in the human being (surgical 
kidney). One massive abscess was seen involving about 
one-third of the organ, and this seems to have had a 
tuberculous basis. Another destructive purulent nephri- 
tis was quoted on page 268 when illustrating 
compensatory hypertrophy. 
Examination of records and preserved specimens of 
nephritis reveals few striking differences which might be 
considered characteristic for the various orders. This 
is possibly due to the fact that the lesions have been 
classified under the same system, a method which has 
proven convenient and consistent. In support of this 
one might refer to that form of nephritis which gives the 
most definite clinical and pathological picture of renal 
disease, namely the chronic parenchymatous. This is 
fairly weU represented in Primates, Carnivora and Ungu- 
lata. In one-fourth of the cases one finds distinct edema, 
especially in the body cavities, cervical and mediastinal 
tissues, and in one-fifth an appreciable grade of anemia; 
uremia was the terminal picture in one animal of 
each order. 
Histology of Nephritis. 
An attempt to discover minute lesions peculiar to the 
various groups gives results that are far from satisfac- 
tory. With reserve it may be said that carnivorous 
