THE URINARY TRACT 269 
enlarged. This teaching is common but I have seen human 
cases without enlargement and only two of the ten cases 
in these animals are noted as bulkier than normal. 
Degenerations. 
Degenerations represent the reaction of the Iddney to 
toxic or infectious agents and might be considered as indi- 
cating the vulnerability of the organ. Their incidence 
does not coincide with that of nephritis as we shall see 
later. Any discussion of degenerative phenomena, and 
especially in the kidney, should be limited by a definition 
of what they are believed to be and their separation from 
inflammations. Degenerations are swellings, granular- 
ities, vacuolizations or infiltrations of tubular epithelium, 
changes which destroy the outline and internal structure, 
perhaps including the nucleus. No changes of the 
glomerular tuft or interstitial tissue are necessary for 
this conception since when these occur the picture 
becomes that of nephritis. In border-line cases it is 
safer to include the case under the latter heading since 
then the physiology is apt to be disturbed, albumen and 
casts appearing in the urine. Degenerations appear in 
various pathological states — toxemia, infection, prolonged 
congestion and others. The first named cause seems to be 
the most important in our records and the seat of the 
toxine production seems to be the intestine. Enteritis 
stands very high in the list of accompanying factors, espe- 
cially in Carnivora, Primates and in Aves. Perhaps the 
most instructive cases are to be found in the Ungulata 
with toxic duodenitis. The kidney in these animals is 
deep red or purple, with a spanned capsule. The section 
surface bulges slightly, is of an opaque, dull purple color 
and shows a congested zone between cortex and medulla. 
Tubular epithelium may be found, under the microscope, 
sufficiently swollen to fill the lumina, in places being like 
ground glass, in others distinctly vacuolated. It cannot 
