576 



Prof. T. G. Brodie. 



then ligatured and the kidney fixed entire in 10-per-cent. formalin solution. 

 After fixation the whole kidney was cut into slices each about 7 mm. thick. 

 The medulla was carefully separated from the cortex, and the latter collected 

 and weighed. Next three small pieces of the cortex, selected from 

 different regions of the kidney, were weighed separately. These were 

 imbedded in paraffin and serial sections mounted. The sections were about 

 8/4 thick. The next point was to determine the number of sections through 

 which a single glomerulus extended. For this purpose ten glomeruli were 

 followed through the series, and the mean number of sections through which 

 one glomerulus ran thus ascertained. Lastly the total number of glomeruli 

 in each section was counted, and the total number for all sections, divided by 

 the average number for a single glomerulus, gave the total number of 

 glomeruli present in that block of cortex. Similar calculations were made 

 from each of the other two pieces. Then, knowing the weights of the three 

 pieces and the total weight of the cortex, the number of glomeruli in the 

 whole kidney was obtained.* The first dog weighed 11 kgrm., its right kidney 

 weighed 34'5 grm.,and the total number of glomeruli was 142,000. A kidney 

 of a second dog, weighing a little over 8 krgrn., contained 125,000 glomeruli. 



Employing a different method, Peterf calculated the number of glomeruli 

 in the dog's kidney as 300,000. He does not give the weight of the kidney, 

 nor does the method he employed appear to me comparable in accuracy with 

 that above described. I have not been able to find any further record of 

 enumerations of the glomeruli in the dog's kidney, and I wish to acknowledge 

 my great indebtedness to Miss M. G. Thackrah for carrying out this very 

 tedious piece of work. 



Measurements of the lumina of the tubules in their several parts were 

 now made, as also approximate estimates of the lengths of the tubules based 

 upon the measurements of Peter. 



The average results obtained from these measurements in the case of the 

 first kidney were : — 



Length. Diameter, 

 cm. fx. 



Proximal convoluted tubule 12 12 



Lood of Henle — 



Descending limb 0*9 10 



Ascending limb 0"9 9 



Distal convoluted tubule - 2 18 



Collecting tubule 2*2 16 



* This is practically the method originally adopted by Huschke in 1828 (' Isis,' vol. 21, 

 p. 550). 



t Peter, ' Verhandl. D. Anat. Ges., Wurzburg,' 1907, p. 120. 



