596 Prof. Brodie and Mr. Mackenzie. On Changes in the ' 



many small vessels passing through the Capsule. Even then there is a 

 distinct escape of blood through the Capsule, and the cortex rapidly pales 

 in colour as the tension falls. The greater the tension at the instant of 

 ligature, the greater is this paling of the cortex, and the sections of such 

 kidneys may show but traces of blood in any of the capillaries, and but little 

 in the veins. 



The change in the shape of Bowman's capsule when the kidney becomes 

 active is very distinctive. It becomes circular or elliptic in section, and 

 there is always fluid between the glomerulus and the capsule wall. In 

 many instances we have noted one other highly suggestive appearance. 

 This is that the first portion of the proximal tubule has, in cases in which 

 a free diuresis was established, been distended so as to appear almost a part 

 of the capsule wall. An instance of this is illustrated in fig. 3. It is a very 

 clear indication that the capsule and the first part of the convoluted tubule 

 have been subjected to a high internal pressure. There are further indica- 

 tions, moreover, that the capsule has been distended to a size much larger 

 than it appears in the section after fixation. The action of a high intra- 

 capsular pressure also adequately explains the change of shape from irregularly 

 quadrangular to spheroidal or ellipsoidal. 



B. The Tubules. — The contrast between the tubules at rest and after they 

 have been in activity is just as striking, and in some particulars has already 

 been described by several observers. In this paper we deal entirely with 

 changes in the total diameter and in the lumen of the tubules, and, moreover, 

 restrict our attention for the most part to the two convoluted tubules. 



The magnitude of these several changes is brought out by the following 

 measurements taken from Experiment 10. The measurements are in microns, 

 and each is the mean of 10 measurements : — 



Expt. 10. — E. kidney resting. L. kidney free. 



Hence 





E. 



L. 





P- 



i*> 



Glomeruli and capsiiles — 









1084 



144-0 





78-4 



103-6 





3-0 



23-8 





93-4 



123-8 





904 



100-0 



Approximate volume capsule ... 



102 



237 



„ „ glomerulus 



92 



125 



fluid 



10 



112 



