Spontaneous Nephritis in Wild Rats. 77 
this character. In few cases fibrous thickening of the capsules 
of glomeruli and cystic dilatation of the same were observed as 
spontaneous lesions similar to certain types of glomerular cysts 
described by E. C. Dickson in his paper on the " Experimental 
Production of Chronic Nephritis in Animals by the Use of Uranium 
Nitrate." 1 These were, however, rare exceptions, whereas in 
uranium poisoning such glomerular lesions seem to be nearly 
constant. Large scars or lesions of the blood vessels were not 
found in any case. 
Of the livers two showed extensive necroses, a disease probably 
familiar to all who handle many guinea pigs. In one case there 
was a slight cellular infiltration of the periportal connective 
tissue and in two sufficient new formation of connective tissue to 
speak of it as an incipient cirrhosis. A condition resembling 
cirrhosis therefore seems to occur spontaneously in guinea pigs 
also, but, so far as our observations go, it is quite rare. Heart 
and aorta were carefully inspected in all cases, but nothing ab- 
normal was noted in any instance. 
45 (570) 
Spontaneous nephritis in wild rats. 
By W. OPHULS. 
Among the very many rats examined in San Francisco for 
plague only very few were found that showed evidences of dropsy 
and of renal disease. One such rat was carefully examined at 
our laboratory through the courtesy of the U. S. Public Health 
and Marine Hospital Service. This rat showed a very marked 
general oedema. The kidneys are small, distinctly granular. 
The measurements are 26 X 14 X 10 mm. The heart is moderately 
but distinctly enlarged, measuring in the formalin hardened speci- 
men from base to apex — 23 mm., the largest transverse diameter 
is 19 mm. and the largest antero-posterior diameter 14 mm. There 
are no gross lesions of the aorta. In sections of the kidneys the 
blood-vessels are found in a normal condition. The glomeruli are 
also quite normal except a few which show slight fibrous thickening 
1 Archives of Internal Medicine, 1909, III., 375. 
