G. Carl Huber 405 
appears to me, briefly as follows: The weight of evidence appears to sub- 
stantiate the statement that the water, the sodium chloride and urea and 
probably other substances existing in a free state in the blood are secreted 
(pass out by filtration or transudation) by the glomerular epithelium. It is 
estimated that 1-12 to 1-14 of the volume of blood entering through the af- 
ferent glomerular vessels is abstracted during the course of the blood through 
the glomerular vessels, so that the blood leaving the glomeruli is thus pro- 
portionately concentrated. To this fact attention may be especially drawn, 
since, as has been shown, practically all the blood found in the capillaries 
surrounding the different parts of the uriniferous tubules is blood which has 
passed through the glomeruli. Uric acid and phosphoric acid appear to be 
specifically secreted, as their quantity cannot be increased by any of the 
known diuretics—Hans Meyer. The evidence is in favor of connecting this 
specific secretion with the epithelium of the proximal convoluted tubules. In 
confirmation of this may be cited the sodium sulphindigotate experiments 
of Heidenhain and Ribbert, the carmine injection experiments of Schmidt 
and Ribbert, the detection of uric acid granules in this epithelium and the 
presence of what has been regarded as secretory granules in the same 
epithelium. To what extent the presence of concentrated blood found in 
the capillaries surrounding the proximal convoluted tubules, having, 
as may be assumed, a larger per cent of uric acid, since this is 
apparently not secreted by the glomerular epithelial, favors the se- 
cretion of this substance by the epithelium of the proximal convoluted 
tubules, cannot be stated. The possibility of its doing so may, how- 
ever, be considered. The experimental evidence appears to favor the 
view that there is a compensatory resorption of water (probably also certain 
salts in proportion to their diffusibility or permeability of the renal cells— 
Cushny) during the passage of the renal secretion through the tubules. That 
this resorption of water takes place in the loops of Henle is probable from 
the experiments of Ribbert, and Hausman and Hans Meyer who obtained an 
increased flow of urine of less concentration after removing the medullary 
portion of one kidney following extirpation of the other. The suggestion is 
here made that this resorption, more especially of the water, takes place in 
the descending limb of Henle’s loop, largely owing to the peculiar flattened 
epithelium possessed by it. That the loops of Henle are longer than gen- 
erally thought is shown by reconstruction, the larger per cent extending 
through or nearly through th entire medulla. These segments of the urinif- 
erous tubules are in relation with capillaries conveying concentrated blood, 
favoring a resorption, Since, as has been shown, the arteriole recte are 
formed almost without exception by a division of certain of the efferent 
glomerular vessels. The blood passing to the medulla through the arteriole 
recte is returned by the venule recte#, which are, if one may judge by corro- 
sion preparations, much more numerous than the arteriole. The loops of 
Henle are, therefore, in relation with numerous capillaries. Whether special 
function may be ascribed to the ascending limb of Henle’s loop and the distal 
convoluted portion, which again has a special epithelium, is difficult to 
state. Heidenhain believed these tubular segments to possess a secretory 
function similar to that possessed by the proximal convoluted portions, bas- 
