CORRELATIVES OF WATER CONTENT 



223 



(fig. 127). One of the questions at stake is, whether plasma dilu- 

 tion is so closely related to rate of excretion that the dilution could 

 inform the kidneys how much water load exists. The correlation 

 is particularly significant when a wide range of water loads or 

 plasma dilutions is investigated; the coefiScient of correlation 

 (+ 0.48) is higher than for any quantity measured in correlation 

 with rate of excretion, except water load itself. It is not the only 



2.8 



2.4 



3 



o 2.0 



y 1.6 



1.2- 



o 



(D 0.8 



0.4 







Doc 



Q ", ur 8 o- 



-* 00 » — O" 



-12 



16 



+20 



-8 -4 0+4 -8 +12 



Plasma Dilution (l/R.l) — percent 



Fig. 127. Eate of urinary water output (% of Bo/hour) in relation to plasma 

 dilution as 1/EI (% of initial state). Two individuals C'(0) and G'(A) ; the 9 tests 

 of figures 116 and 117 plus 7 more tests in which water was given by stomach, together 

 with the 6 tests of figures 120 and 121 in which water was first denied, are represented. 

 Two of these tests (on dog G') have the successive points connected by lines. Excluding 

 the 6 water privation tests, the correlation coefficient in positive loads is + 0.48. 



correlation, and to designate plasma dilution as the cause of diu- 

 resis would be misleading. To conclude, on the contrary, that 

 "changes of blood concentration and volume are scarcely detectable 

 in diuresis" (Adolph, '30, p. 63), merely because circumstances 

 may be found in which the correlation is poor, is erroneous. To 

 conclude that only a single factor of any kind governs the rate of 

 water excretion may be equally blinding. 



