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DISEASES OF THE UBINABY APPABATUS. 



We shall only treat of such matters the recognition of which is 

 important from a practical standpoint. 



I. Albuminuria. Ancient theories upon the pathology 

 OF ALBUMINURIA. Until recent years an increase of the blood 

 pressure in the kidney has been considered by a great number of 

 authors as necessarily the cause of albuminuria. It was thought 

 that albumin — -a colloid substance, in opposition to crystalloids 

 (salts, sugar, etc.) — could only pass through the animal tissues by 

 an increase of the pressure of filtration (Malpighiau bodies). But 

 this doctrine has against it this physiological fact that albumin will 

 pass through animal membranes as easily as many other substances. 

 The process of nutrition should be rendered impossible if this 

 property of albumin were wanting. 



In 1879 Runeberg, relying upon physical experiments (filtration 

 of albuminous solutions through dead animal membranes), created 

 a new theory on the pathology of albuminuria. He looks upon 

 the lowering of the normal pressure in the glomeruli as the cause of 

 albuminuria. An objection which has been made against Rune- 

 berg's theory is that the dead animal membranes and the mem- 

 branes of the living organism may act differently under albuminoid 

 solutions, and that some chemical phenomena, such as the appear- 

 ance of ascites through the increase of the pressure in the portal 

 vein, or the escape of albuminous serum into the pulmonary alveoli 

 by the increase of blood pressure in the lung (pulmonary œdema), 

 testify absolutely against it (Senator). Ribbert and Cohnheim 

 afterward proposed two different theories — both, however, unten- 

 able : in the first, the capillaries of the glomeruli, and in the second, 

 the epithelium of these capillaries, would have the property, when 

 in a normal state, of retaining the albumin, while all the other 

 capillaries and epithelium would be passed by this substance. 

 Heidenhain attributes to the epithelial cells of the glomeruli se- 

 creting properties ; he makes true glandular cells out of those 

 having the function of urinary secretion, while it would retain the 

 albumin. According to Heidenhain's theory of secretion, albumin- 

 uria is produced when the epithelium of the glomeruli is altered or 

 destroyed. 



Generally admitted up to date, this theory has beeu successfully 

 combated by Senator.^ This author points out that the epithelial 

 cells of the glomeruli — flat cells, which are poor in protoplasm— 



1 Senator: Berliner klin. Wochenschr., 1885. 



