594 Prof. Brodie and Mr. Mackenzie. On Changes in the 



4. With the ureter ligatured. This we term an " active obstructed " 

 kidney. 



We soon found that the different parts of the renal tubule, and more 

 especially of Bowman's capsule and the glomerulus, varied considerably in 

 size in different animals, so that it is necessary in making comparisons to 

 use only, in the first instance, opposite kidneys in the same animal. Hence, 

 our series of experiments comprises each possible combination in the above- 

 named types of experiments. 



All our experiments were performed upon cats anaesthetised with a 

 mixture of chloroform and ether. 



In all experiments, the kidney was removed and fixed in the following way. 

 It was first carefully freed from subperitoneal fat, and a ligature then tied 

 tightly around the pedicle close to the hilum. A second ligature was next 

 tied around the pedicle a little nearer the aorta, and the pedicle divided 

 between the ligatures. The object of ligaturing the pedicle was to keep the 

 urine within the tubules, and as far as possible in the position it occupied 

 at the instant of ligature. The kidney was dropped intact into a beaker of 

 20-per-cent. formalin made up with 09 per cent. NaCl. The beaker and 

 solution had previously been weighed, and it was now weighed a second 

 time, giving the weight of the kidney. At the end of an hour, the kidney 

 was sliced into thin sections, fixation in formalin completed, and the pieces 

 imbedded and sections prepared. The following measurements were then 

 taken : — 



1. An equatorial diameter of the capsule at right angles to the polar 

 diameter. 



2. The polar diameter, i.e. one passing through the point of entrance of 

 the blood-vessels. 



3. The greatest distance between the glomerulus and the capsule if the 

 two were not in contact. 



4. The maximal diameter of a typical proximal convoluted tubule. 



5. The diameter of its lumen. 



6 and 7. Similar measurements of a typical section of the distal convoluted 

 tubule. 



The glomeruli measured were taken at random, care being exercised only 

 to measure those in which the section passed centrally. This was generally 

 fairly easy to attain by taking those which showed the point of entrance of 

 the blood-vessel into the glomerulus. From these measurements, calculations 

 were made of the approximate volumes of the capsule and the glomerulus 

 respectively. To obtain these, we regarded the capsule as equal in volume 



