63 



a pea. Microscopical sections through these abscesses showed that 

 they were walled off from the kidney structure proper by beginning 

 connective tissue formation. The abscess cavity was filled with 

 polynuclear leucocytes, some of them very markedly disintegrated. 

 The epithelial structure of the kidney proper showed some paren- 

 chymatous degeneration. 



ATROPHY OF A KIDNEY. 



On one occasion we have seen a kidney represented by a very 

 small flattened mass of tissue, the nature of which was not quite clear 

 until microscopical examination showed a few fairly well-defined 

 glomeruli and a few cell groupings suggestive of tubules. Whether 

 the condition was congenital or acquired is not known. The other 

 kidney appeared to be normal in every respect. There was no evi- 

 dence of compensatory hypertrophy. 



VESICAL CALCULI. 



The bladder of rats very frequently contains very irregularly shaped, 

 rough, somewhat branching concretions. These concretions are 

 rather soft and tough and are dirty white in color. 



In addition to these concretions we have seen several cases of well- 

 marked vesical calculi. In one case 21 smooth round stones which 

 conipletely filled the bladder were found. The total weight of the 

 stones was 3.8 grams. In another case 6 calculi were found, the total 

 weight of which was 7.8; the largest one weighing 5 grams. In a third 

 case 8 smooth, round stones weighing 1 .7 grams were found, the largest 

 of which weighed 0.6 gram. The last two cases were female rats; 

 the sex of the first was not recorded. 



In each of these cases the bladder showed to the naked eye very 

 marked evidence of inflammation. The mucous membrane was red- 

 dened, villous, and covered with tenacious mucus. In one case in 

 which microscopical examination was made the mucous membrane 

 was found to be covered with pus cells, the surface layers of which 

 were undergoing degeneration. 



Diseases of the genital tract in the human race analogous to those 

 mentioned below are so generally regarded as due for the most part 

 to infections from impure sexual relations that it was a distinct sur- 

 prise to find such lesions in rodents. 



In the male abscesses are occasionally met with in connection with 

 the seminal vesicles. We have seen them varying in size from a 

 pea to a sac whose contents would have measured 3 or 4 cubic centi- 

 meters. In the female purulent collections in the horns of the bifid 

 uterus are encountered, but they are rare. We have seen cases that 

 were anatomically exactly like the purulent lesions so commonly found 

 in the fallopian tubes of women. In one case one horn of the uterus 



