ANALYSIS OF THE URINE. 



339 



possess all the characters of the endothelial cells of the serous 

 membranes, and that it is rash to attribute secreting properties to 

 them ; also that in the foetus and the newborn, whose cube-shaped 

 glomerular epithelial cells are richer in protoplasm and quite 

 similar to the glandular cells, the urine is albuminous to a normal 

 degree. Finally, quite a number of clinical and experimental facts 

 have been observed which contradict Heidenhain's theory. 



Pathology of albuminuria according to Senator. Con- 

 trary to the generally admitted opinion and that of the majority of 

 physiologists. Von Wittich, Henle, and Kiiss had maintained that 

 the product of filtration in the glomeruli is albuminous. Senator^ 

 gives reasons of a purely physical kind in order to explain the 

 absence of albumin in the normal urine : the pressure in the capil- 

 lary glomeruli, he says, is stronger than in any other part of the 

 body ; much liquid and little albumin, therefore, passes through 

 their walls ; the product of filtration is here poorer in albumin 

 than the other products of transudation — than the cerebro-spinal 

 liquid, for instance, which only contains traces; on the other 

 hand, the secretion of the epithelium of the renal canaliculi also 

 helps to dilute the quantity of albumin contained in the liquid that 

 has left the glomeruli. All these circumstances together make it 

 clear that the proportion of albumin contained in the urine is so 

 small that it would not be possible to put it in evidence by means 

 of our reactions. 



But this albuminous solution may become concentrated — in other 

 words, albuminuria may be produced — when one or several of the 

 four factors coming into play in the filtration begin to act, viz. : 

 the pressure of filtration, the constitution of the membrane, the com- 

 position of the blood, and the temperature. 



1. Modifications of the pressure of filtration. Increase of the arte- 

 rial pressure alone lessens the relative proportion and increases the 

 absolute quantity of albumin in the product ; but when the urine be- 

 comes less w^atery (by violent muscular efforts, or perspiration, etc.), 

 the relative quantity of albumin must necessarily increase : there is 

 then a certain degree of albuminuria. The effects of venous stagnation 

 are nearly the same as those of augmentation of arterial pressure : 

 the distended veins compress the uriniferous canaliculi ; they pro- 

 duce urinary stagnation and a renal œdema, which is accompanied 

 by an albuminous transudation through the interstitial capillaries 



^ Senator : Die Albuminurie im gesunden und kranken Zustande, 1882. 



