62 



the sac of the hernia. The other division of the uterus was dilated 

 and full of pus. The hernial sac is rarely situated in the median line. 

 One inguinal hernia has been seen. 



GENITO-URINARY TRACT. 

 NEPHRITIS. 



Nephritis is a rather common condition in rats. Among the large 

 (old) ones it wUl be found probably once in every fifteen or twenty 

 examined. It has been found to be especially frequent in rats that 

 are suffering from the leprosy-like disease, as probably two-thirds of 

 those having that interesting infection will show marked evidence of 

 nephritis. The kidney is usually brownish or grayish, mottled, friable 

 and often shows cysts upon the surface and in the substance of the 

 organ. Some of these cysts may be as large as a pea, or indeed even 

 much larger. The capsule strips very readily. 



Microscopically the lesions are found to be due partly to epithelial 

 and partly to interstitial change. There is a marked increase of 

 connective tissue rather irregularly distributed throughout the organ. 

 The epithelial cells show various degrees of degeneration; the nuclei 

 are stained very lightly, or not at all; granular change of the proto- 

 plasm is well marked. Some tubules are encountered in which the 

 epithelial cells are entirely wanting. 



Cyst formation is a conspicuous feature in many of the cases. 

 These cysts vary considerably in size, are often filled with granular 

 debris, and are more or less completely lined with epithelial cells 

 which are sometimes fiattened. At times the epithelial lining is 

 entirely wanting. The glomeruli, on the whole, -appear to be better 

 preserved than are the tubules. Occasionally areas are found in 

 which there is a very marked round cell infiltration between the 

 epithelial structure. One of the most marked cases of nephritis we 

 have observed was in a large female Mas alexandrinus, in which both 

 kidneys were almost entirely replaced by cystic formation, the largest 

 cyst being perhaps 3 centimeters in diameter by 4 centimeters in 

 length, and full of a clear, watery fluid. So extensive was the cystic 

 formation that only a few remnants of kidney tissue remained. Micro- 

 scopical examination showed a marked increase in the capsular and 

 interstitial connective tissue, a shrinking of the glomeruli, which were 

 surrounded by well-marked fibrous capsules, and extensive cyst for- 

 mations. The lining of some of these cysts was made up of epithelial 

 cells. Others were quite bare. This rat had, in addition, a large, 

 rough calculus in the urinary bladder. 



ABSCESS OF THE KIDNEY. 



A female Mus norvegicus had on one side of the neck a large cavity 

 full of caseous matter. In each kidney there were five or six circum- 

 scribed collections of pus, the largest of which was about the size of 



