Spontaneous Lesions in Rabbits and Guinea Pigs. 75 
meable to Sudan III under the conditions of the experiments 
already described. 
The authors demonstrated the general facts in this connection 
pertaining to rubber and gold beaters' skin. 
Experiments along these lines, with additional membranes, 
pigments and liquid media, are in progress, in an effort to obtain 
further knowledge of the functions of membranes in diffusion. 
44 (569) 
Occurrence of spontaneous lesions in kidneys and livers of 
rabbits and guinea pigs. 
By W. OPHULS. 
[From the Pathological Laboratory of Cooper Medical College, 
San Francisco.] 
In view of the importance of the occurrence of spontaneous 
lesions in the kidneys and in the livers of rabbits and of guinea 
pigs in reference to the experimental work on these organs, Dr. 
E. C. Dickson and myself have made a careful study of these 
organs and incidentally of the heart and of the aorta in fifty 
rabbits and in one hundred guinea pigs. The animals used were 
partly fresh animals from the market, partly animals raised at the 
laboratory. 
Many of the rabbits had been used in the physiological labora- 
tory and had been killed immediately after the experiments; some 
died of coccidiosis; a few had been injected with material sup- 
posedly containing pneumococci without result; others had never 
been used. Several old rabbits that had been in the laboratory for 
a year or longer were especially selected on account of the greater 
likelihood of the existence of renal or hepatic lesions in them. 
Twenty-eight rabbits, among them some of the old ones, had 
entirely normal kidneys, nine showed slight parenchymatous 
lesions, three a few small areas of cellular infiltration. In ten we 
found scattered small areas in which were marked interstitial 
lesions with the formation of small depressions on the surface. 
Four of these proved to be radially arranged chronic septic foci 
which extended from the vicinity of the papilla to the outer surface. 
