SECRETION AND EXCRETION 



335 



secretion of urine increases and conversely. Though the relationship 

 is not as evident hi the second experiment as in the first, it is still quite 

 definite. 



Injection of 20 gm. cane sugar in 40 c.c. water: 



Injection of 50 gm. cane sugar in 100 c.c. water: 



[The choice of sucrose for these experiments is unfortunate since, as 

 M. H. FISCHER and WOODYATT have shown, sucrose dehydrates and 

 offers free water to the kidney. Gelatin and gum arabic raise the 

 coefficient of friction without increasing urine as STARLING has shown. 

 There is consequently no foundation for the conclusions of LAMY and 

 MAYER. Tr.] 



The Concentration of the Glomerular Filtrate. 



The filtrate through the glomerular filter probably shows a concen- 

 tration of crystalloid constituents not much different from that of the 

 blood plasma, although a certain selection and redistribution in the rel- 

 ative proportion of the crystalloids by the renal filter is conceivable. 

 The blood shows a depression of the freezing point of about 0.56, 

 whereas the urine of man in health may vary between 0.07 to 3.5. 



For a urine of higher osmotic pressure than the blood, the filtration 

 theory must look for support to the assumption that water must be sub- 

 sequently withdrawn from the diluted filtrate in the first portion of the 

 urinary tubules. The investigations of J. DEMOOR seem to me to be of 

 especial importance for the assumption of a subsequent change in con- 

 centration in the urinary tubules. This author perfused hypotonic 

 and hypertonic salt solutions through the renal artery and while he 



