A. Hunter and W. R. Campbell 181 
the haphazard procedure followed might reveal some rough re- 
lationship between the plasma and the urinary concentrations of 
creatinine. As far as comparison of the two in individual cases 
goes, no indication whatever of any such relationship can be 
detected. On the other hand, when regard is paid only to the 
various averages scattered through Table I, a certain degree 
of correspondence becomes apparent. Indeed, if one limits the 
attention to the averages in which the number of urines concerned 
is more than ten, the correspondence becomes a fairly close 
one. The averages in question are for plasma U.87, 0.89, 0.99, 
1.03, 1.04, 1.09, and for urine 95, 124, 141, 166, 157, 163. It 
seems probable, therefore, that the plasma concentration is at 
least one among the many factors upon which the concentration 
of creatinine in the urine must depend. 
The Distribution of Creatine in Blood. 
The greater number of our creatine determinations had been 
already carried out, before it became obvious, through the work 
of Wilson and Plass,'* Greenwald,*! and ourselves,* that the 
method employed, which in the beginning was the only one avail- 
able, fell more than a little short of the accuracy necessary to 
our purpose. It seemed then best, instead of turning to other 
methods of as yet unproved reliability, to complete the series as 
it had been commenced, and to hope that, when due allowance 
had been made for the errors incurred, the results might prove to 
be not altogether without significance. The hope has been, we 
think, to a certain extent realized. At the same time we cannot, 
for conclusions based. upon admittedly inaccurate data, claim 
more than a provisional validity. In the discussion which fol- 
lows we wish therefore to be understood as dealing for the most 
part with suggestion rather than proof. Many, if not all, of the 
deductions drawn from our figures demand confirmation by a 
less dubious analytical method. 
On one point perhaps the results do actually amount to a 
demonstration. In every case the plasma yields for creatine a 
figure so far below that of the blood, that there can hardly exist 
a doubt that the bulk of that substance is carried in the cor- 
31 Greenwald, I., Proc. Soc. Exp. Biol. and Med., 1916-17, xiv, 115. 
