Report on the Bacteriology of Water. 445 



Doubling periods : 



36 72 fi = 5.0 P.M. 5.37 P.M. = 37 minutes at 28 -9 29 '028 '5 C. 

 72 144 ,,=5.37 ,,-6.13 =36 28 '5 28 '25 C. 

 144288 = 6.13 6.48 - 35 28 '2529 '0 C. 



Reckoned back : 



436 -0218 '0 M = 6.34 P.M. 7.9 P.M. = 35 minutes at 28 -629 '0 C. 

 218-0 109-0,, = 5.58 ,,6.34 =36 28 '3 28 -228 '7 C. 

 109-0 54-5 = 5.20 5.58 =38 28 -8 -28 '3 C. 



Another partial filament was taken at 8.15. 

 Doubling periods : 



59 -5119 n = 8.15 P.M. 8.49 P.M. = 34 minutes at 2828 -25 C. 



Reckoned back : 



14472 M = 8.25 P.M. 9.25 P.M. = 60 minutes at 28 '2528 '528 C. 



There can be little doubt that here we have a case of slowing of 

 growth after five hours' exposure to the temperatures given ; i.e.. the 

 measurements are here of a piece running down from exhaustion. 



On December 3 spores were put at 22 at 9 A.M., and into measure- 

 ment at 2.35, as follows : 



Normal doubling periods : 



116232 n = 3.5 P.M. 3.35 P.M. = 30 minutes at 28 '2528 '628 -5 C. 

 232464 = 3.35 4.6 = 31 28 -531 C. 



Doubling periods : 



87-76175-5 n = 2.54 P.M. 3.24 P.M. = 30 minutes at 28 '25 28 '6 28 -5C. 

 175 -5 351 '0 = 3.24 3.54 = 30 28 '530 '5 G. 



Calculated back : 



495 -0247 -5 n =-- 3.37 P.M. 4.10 P.M. = 33 minutes at 28 -531 '1 C. 



247 -5 123 '75 = 3.7 ,,3.37 =80 28 -25 28 '6 28 '5 C. 



The most interesting feature in this curve was to see how a steady 

 slow rise of temperature did not prevent a second doubling at nearly 

 the maximum speed. I was not able to measure any further, but 

 saw enough to convince me that the organism was breaking down 

 soon after from exhaustion. 



On November 7 spores were sown in normal 10 per cent, gelatine 

 at 1 P.M., and put into incubator at 22 C. At 5.30 the germinated 

 rodlets went into the Sachs' box at 30 C., and at 5.54 the measure- 

 ments began as follows : 



Doubling period (nearly normal) : 



29 -2558 -5 ju = 5.54 P.M. 6.23 P.M. = 29 minutes at 29 -52932 -6 C. 



