270 DISEASE IN WILD MAMMALS AND BIRDS 
be stated absolutely which part of the tubule is usually 
affected; it seems more often the distal convoluted por- 
tions than other subdivisions. Glomeruli may be full of 
blood but there is no increase in cell^ nor any material in 
the capsular space. The urine is dark and may or may 
not show albumen. The kidney of kangaroos with strepto- 
thricosis is similar to the picture just given. 
Mammals have shown a percentage incidence of renal 
degenerations of 4.8 per cent, while Aves show only 3. per 
cent. In order of incidence the carnivores head the list 
followed by Lemures, Accipitres, Rodentia, Primates and 
Marsupialia; the remaining groups show but a few cases. 
A form of degeneration is sometimes seen in the avian 
kidney the seat of excess urate collections, especially 
when these are arranged as so-called uratic infarcts. Tliis 
last term has been applied to the streaking and mottling 
of human kidneys by the accumulations of these salts in 
a manner believed by some to be related to the formation 
of uratic calculi. The epithelium of such a kidney may 
show granularity and collections of acids and salts have 
been found in the lumina. In the bird on the other hand 
one frequently sees masses of urates in one lobule, or a 
part thereof, arranged to simulate closely the common 
infarct shape. Secretory cells in the affected area are 
hydropic, with absent or dislocated nucleus, or again they 
present a densely basic-staining protoplasm. This form 
of kidney is well seen in what has been called here an 
uratic serositis, a coating of all somatic free membranes 
with a thin, white, granular film. We have tried with 
many techniques to preserve one of these cases but the 
deposit either dissolves or the whole specimen becomes 
opaque. Although the term infarct is applied to these 
lesions, they are of course not infarcts in the customary 
use of the term. True infarcts are exceedingly uncommon 
and, with the exception of one case which became infected 
and suppurated, have been negligible in our material. 
