16 
TABLE II 
Calculated Dilutions and Calculated and Observed MPN's 
of Subsurface Samples 
Number of Calculated from Observed 
samples radioactivity chlorinity MPN's/m1. 
Geometric mean 12 1/640 1/160 
of dilutions 
Geometric mean 20 790 70 
on MPN‘'s/ml. 11 3,600 170 
