406 Profs. Percy Frankland and Marshall Ward 



As regards the discrepancy between the first doubling period and 

 the rest. I have little doubt it is explicable with reference to the 

 process of germination. It must be noted that the initial length 

 (4 /t) is not that of a free rodlet working up its food-materials from 

 the broth, but of rodlet plus spore, and presumably still utilising 

 unexpended stores from the spore. To make the comparisons fair, 

 therefore, we ought to neglect this first period. 



On July 21 and 22 the following observations were started with 

 cultures in fresh broth : 



Spores sown 8 P.M. were put at once into Sachs' box at 19*5 C., 

 falling to 18-75 at 9.30 P.M. 



On July 22 the growths, followed for 1 hour and 10 minutes, gave 

 the doubling period : 



99198 n in 65 minutes at 1716 '75 17 0. 

 Or, calculating back : 



225112-5 p. = 8.22JA.M. 9.10 A.M. = 48 minutes at 16-7517 0. 

 Normal doubling period : 



112224 n = 8.22 A.M. 9.10 A.M. = 48 minutes at 16' 75 17 C. 



This culture formed spores by 9 A.M., July 25, having been at 

 16 19 throughout. 



On July 22 a culture started in broth at 17 C. at 8 A.M., had ger- 

 minated out about noon, and the measurements were made from 

 4.55 P.M. to 8.28 P.M. Sachs' box, &c., as before. 



Here the doubling periods were as follows : 



1. 38-25 76 -5 /j. = 68 minutes at 19 18 '2 C. 



2. 76-5 153 = 72 18 -2 18 C. 



3. 153 306 = 73 1818 '2 C. 



Normal doubling period : 



56'5 113 /j. = 5.30 P.M. 6.41 P.M. = 71 minutes at 18'5 18 C. 

 113226 = 6.41 7.54 = 73 18 C. 



This culture had formed spores at 9 A.M. on the 25th, having been 

 at 16 19 in dark Sachs' box the whole time. 



If we calculate at other points in the curve, we get doubling as 

 follows : 



112-5225 n = 6.40 P.M. 7.54 P.M. = 74 minutes at 18 C. 

 50 -5101 = 5.20 6.29 = 69 18 -518 C. 



On July 24 I sowed spores in broth at 2.30 A.M., and put at once 

 into the Sachs' box at 17 C. The temperature remained constant 

 through the early morning, and measurements were made as fol- 

 lows : 



