Report on the Bacteriology of Water. 



447 



cooling of the cover-slips, so that here, at any rate, the effect is at 

 least in part due to temperature. 



These reflections seem justified by the following measurements in 

 the culture last referred to : 



Curve 152, p. 442. 



We see that the growth had become very much slower, and at last 

 had all bat ceased. At 8.30 next morning the short crop had begun 

 to try to form a few feeble spores ; two control cultures, at 22 C. 

 all the time, had grown more evenly, and developed a crop probably 

 100 times as big, and had not yet passed over into the spore stage, 

 though they did so during the succeeding forty-eight hours, and then 

 represented a far larger crop, with much more numerous and well- 

 developed spores. 



Further criticism of these November 7 experiments confirms the 

 conclusions already arrived at. Thus, during the first hour at 29'5, 

 rising to 32'6 C., and therefore at the large range of 3'6 C. the 

 doubling nevertheless only took twenty-nine minutes ; whereas after 

 three hours at similar temperatures, 29'0 32'25 (a range of 3'25) it 

 had not anything like doubled in two hours, i.e., the time of exposure 

 to this range tells by slowing the doubling period. 



On December 2 spores were pat in, at 22, normal gelatine at 9 A.M., 

 and into measurement at 2.30 P.M., as follows : 



