68 



J0RN Hess Thaysen 



Fig. 4 shows the relationship between the S/P (secretion/ 

 plasma) concentration ratio for urea and the rate of secretion 

 of sweat, parotid saliva, tears and pancreatic juice. 



In tears and in pancreatic juice there is apparently dif- 

 fusion equilibrium between the secretion and the plasma at all 



2.0- 



1.5 



1.0 



0.6 



0.8 



SECRETORY RATE 

 Fig. 4. The relation between the S/P ratio for urea 

 and secretory rate in sweat, parotid saliva, tears 

 and pancreatic juice. From the data of 1 : Araki 

 and Ando (1953) (the curve is shown as a 

 broken line because it represents the approximate 

 mean of two determinations and because secre- 

 tory rate cannot be directly compared to that of 

 the other glands); 2: Albrectsen and Thaysen 

 (1955); 3: Thaysen and Thorn (1954); 4: Bro- 

 Rasmussen, Killmann and Thaysen (1956). 



rates of glandular activity. On the basis of these findings no 

 statement can be made about the existence or non-existence 

 of an internal circulation of water in these glands. 



In sweat and in parotid saliva S/P urea varies with the 

 rate of secretion. In the sweat S/P urea decreases from 

 2 or 3 at the low secretory rates to about 1 when sweating 



