A New Conception of the Glomerular Function. 583 



resting kidney. In the third place I have often observed the following 

 changes during the course of an oncometric experiment, viz., a large 

 increase in the volume of the kidney, a free flow of urine, but a decrease in 

 the rate of blood flow through the kidney. Here the plethysmographic 

 increase is due to an accumulation of urine within the capsules and tubules. 

 Lastly, if we examine a kidney at the height of a diuresis we always find it 

 very hard and tense. The Capsule is distended to its fullest degree. If we 

 attempt to make such a kidney expand still further by temporarily clamping 

 the vein we fail completely. We see then that some of the tension set up 

 by the blood-pressure in the glomeruli is transmitted through the capsule 

 wall and the walls of the tubules to the general renal tissues. How much 

 pressure is thus transmitted depends upon the resistance to distension offered 

 by Bowman's capsule and the walls of the convoluted tubules. Their 

 structure, particularly that of the capsule, indicates that they probably offer 

 a fairly considerable resistance. We could get an estimate of this by finding 

 the difference between the blood-pressure in the glomeruli and the general 

 tension of the kidney substance within its Capsule. I made some attempts 

 to measure this latter during active diuresis, but at present have not obtained 

 any very accurate results. As far as they go they indicate a tension of about 

 40 mm. Hg. 



If this be the true meaning of the kidney Capsule then, if we remove it 

 before exciting diuresis, the kidney ought to expand still further as compared 

 to the intact one, and the amount of that further expansion should depend 

 upon the general rigidity of the kidney substance and the amount of con- 

 nective tissue it contains. Our experiments proved this to be the case. The 

 weight of such a kidney compared to one with the Capsule untouched was 

 always greater, especially in the rabbit's kidney. In the cat there are 

 a number of incomplete septa running transversely towards the 

 hilum, and on active diuresis the kidney substance bulges notably between 

 these, giving the appearance of constricted grooves in the bottom of which 

 veins run. This relatively greater increase in volume of the kidney as a 

 whole is also found in the several parts of the tubule, and when we measured 

 the tubules and glomeruli in such kidneys, the differences were very distinct. 

 For instance, in one experiment the right kidney was untouched, and the left 

 decapsulated. The following approximate volumes of the capsule and 

 glomerulus after diuresis were obtained : — ■ 



E. L. 



Volume of capsule 205 257 



„ glomerus 128 151 



fluid 27 106 



