EFFECTS ON THE URINARY TRACT 383 



especially in the later stages (Table 6). The percentage of dry substance in 

 the kidney remains nearly constant. 



Figures 97 and 98 are from photographs of sections showing typical changes 

 in the renal cortex of the adult albino rat as a result of acute inanition (on water 

 only) . 



Functional Changes, Hibernation, Etc. — Some structural changes observed 

 during inanition or hibernation, and relating especially to the renal cell function, 

 will now be considered. 



Sauer ('95) studied the kidney-cells in the dog, rabbit, hedgehog, rat, mouse 

 and guinea pig, contrasting the condition of relative anuria (produced by feeding 

 dry food only; also by total inanition in rabbits and white mice) with that of 

 polyuria (produced by intravascular injection of urea, etc.). He found no 

 secretory changes in the brush border of the renal cells (as claimed byDisse '92); 

 also no changes in the rod-like structures of Heidenhain. In the fasting (or 

 thirsting) animals with urinary suppression, the cells appeared taller, and the 

 lumen of the tubule smaller; after maximal secretion, the cells were reduced 

 in height and the lumen became larger. 



Zanier ('96) found no diminution in the granular "bioblasts" of Altmann 

 in the kidney and liver-cells of the fasting frog or rat. Likewise Sjobring ('00) 

 saw no change in the mitochondria (chondriosomes) of rabbits fasting 1 or 2 

 days. 



In the hibernating marmot, R. and A. Monti ('00) noted the appearance in 

 the renal epithelium of numerous granules, which were thought to represent 

 excretory substances. The brush border is an integral cell constituent, not 

 merely a functional stage. The width of the tubular lumen varies according to 

 functional condition. 



Baroncini and Beretta ('00) found that in hibernating bats (Myoxus, Vesper- 

 tilio and Vesperugo) the kidney-cells present a progressive degree of cloudy 

 swelling in the renal labyrinth; also the appearance and progressive increase of 

 fat droplets, and (sometimes) the exit of the nucleolus, in the convoluted tubules 

 and loops of Henle. No changes were observed in the collecting tubules and the 

 ducts of Bellini. 



Disse ('00, '00a, '02) claimed that the functional changes in the renal epi- 

 thelium can be ascertained only by comparing the structure during active 

 secretion with that found in the quiescent condition. A study of these condi- 

 tions in the bat (Nannugo pipistrellus) during activity and hibernation supports 

 Disse's theory that the brush border represents a resting condition, being 

 liquified and evacuated during renal secretion. 



Ferrata ('05, '05a), however, could find no appreciable change in the brush 

 border of the cells in the convoluted tubules and loops of Henle in the marmot, 

 hedgehog, bat and tortoise (Emys) during activity and hibernation. In hiber- 

 nation the lumen of the tubule becomes smaller and the cytoplasmic granules 

 of all kinds more numerous. As previously mentioned, Takaki ('07) concluded 

 that the granular metamorphosis of the basal cytoplasmic rods in the renal 

 epithelial cells of fasting or thirsting white mice represents a stage in the normal 

 process of secretion. 



