THE URINARY TRACT 285 
the kidney in a mammal was found in a Gray Squirrel 
{Sciurus carolinensis pennsylv aniens), a solid gray 
nodule composed histologically of large and small deeply 
staining cells, many containing large vacuoles and fitted 
with a small dark nucleus. The arrangement of the ele- 
ments was in irregular acini or bundles and thereby 
suggested the tumor known as hypernephroma, A small 
nodular adenoma was found at the upper end of the right 
kidney in a common opossum {Didelphys virginiana) 
and seemed to be purely of renal construction in that an 
attempt to retain tubular arrangement was evident. 
Twelve primary tumors occurred in birds, and of these 
five were found among parrakeets, they being curiously 
enough all of the same type. These cases were all dis- 
covered in the undulated grass variety {Melopsittacus 
undulatus tt^^^ ) and, because of this fact and their 
histological similarity, have excited interest. Grossly 
they are irregularly nodular or lobulated tumors usually 
springing distinctly from one lobe, but sometimes 
destroying the whole organ; they are soft, resilient and 
hold their place well during manipulation. Sometimes 
one may detect the topography of the renal lobes on cross 
section while at other times the mass is homogeneous. 
Microscopically one finds the structure of papillary 
adenoma with cystic formations or the production of 
atypical solid nests of epithelia which would have to be 
called cancerous, for they certainly make no attempts to 
retain acinus or duct groupings. Carcinomatous areas 
have been discovered in two of these cases, not in the 
other three, which have been called papillary adenoma. 
One of the tumors was subjected to many sectionings and 
different stainings techniques to discover, if possible, 
animal and vegetable parasites ; this search failed. One 
of these tumors produced hemorrhage by rupture of a 
pyramid but extension to adjacent tissue and metastases 
have not been seen. Pathologically these must be classi- 
fied with the tumors but because of the number of closely 
similar growths in the same avian species housed in the 
