Physiology. — ''The conduct of the kiclnei/s toivards some isomeric 

 sugars {Glucose, Fructose, Galactose, Mannose and Saccharose, 

 Maltose, Lactose):' Bj Prof. H. J. Hamburger and Dr. R. 

 Brimkman. 



(Communicated in the meeting of September 28, 1918). 



It has been proved by former researclies '), that ihe glomerulus 

 epithelium of the kidney of the frog is able to hold back glucose 

 if the solution which is passed through the vascular system has a 

 suitable composition, if one passes through the arteria renalisofthe 

 frog the following Ringer's solution: NaCl 0,7 7„, KCM 0,01 "/o, CaCl, 

 0,0075 7„, NaHCO, 0,02 " „, in which 0,1 7, glucose has been dis- 

 solved, then an artificial urine is exci-eted containing 0,07 °/o glucose ; 

 0,03"', glucose has thus been retained by the glomerulus epithelium. 

 If however the Ringer's solution contains 0,285 °/„, i.e. a quantity 

 that corresponds to the titrational alkalicity of the seKum of the 

 frog, then much more sugar than 0,03",, is held back and not 

 seldom the urine is free from sugar. 



This phenomenon proves that the glomerus membrane, which is 

 permeable to salts, is under physiological conditions impermeable to 

 the also crystalline glucose. 



In order to come to an explanation of this remarkable and useful 

 contrast it seemed interesting to investigate how the glomerulus 

 membrane would behave towards laevulose, galactose and mannose, 

 all isomeric to glucose, and also towards the mutually isomeric 

 saccharose, lactose and mannose. 



Let us begin with the four first-named. 



As is well known, the structural formula of the monosaccharides 

 (OpH,,Oj can be re[)resented in the following way : 



1) Hamburger and Brinkman: Proceedings of the Royal Acad, of Sciences Section 

 of Jan. 27, and Sept. 29, 1917. Also: Biochem. Zeitschr. 88, 97, 19-18. 



