358 



Profs. Percy Franklaiid and Marshall Ward. 



one to about 34 C., as shown by controls with thermometers in the 

 water. 



Two samples of the water of the un exposed flask, taken at 

 4.30 P.M. on September 5, gave 1,575,860 and 1,285,388 as the num- 

 bers per c.c. ; total, 2,861,248; mean, 1,430,624 per c.c., suggesting 

 that the sojourn in distilled water at that temperature, even in the 

 dark, causes the death of large numbers of this bacillus. 



Of two samples taken at 4.30 from the flask t) (2), which had been 

 exposed for six and a half hours, neither plate gave any sign of life 

 after ten days' incubation, whence we may assume that neither 

 sample contained a living germ. 



These two flasks were put in a cool cupboard over-night temper- 

 ature = 15 C. and again put out on the 6th September from 9.30 

 to 4.30, so that the exposed flask ij (2) received another good six 

 hours of bright sun, for the day was brilliantly fine again. 



After the exposure, a plate was made from each flask. That from 

 T) (2), the one exposed to the sun, gave no signs of life though incu- 

 bated for ten days ; the other showed 560,000 per c.c. 



It seems probable, therefore, that in the case of Bacillus // the im- 

 mersion in sterile water at 33 34 C., even in the dark, is more or less 

 fatal, for we see the bacteria are reduced from over a million and a 

 half per c.c. to nearly half a million per c.c. At the same time it 

 seems pretty clear that when exposed to light at the same time the 

 mortality of the bacilli is much greater. The inference appears fair, 

 bat there is naturally some dissatisfaction to be felt with these 

 negative results. 



The following table N" summarises these facts : 



Table N. Experiments on Insolatic 



* There were 32 squares, averaging about 1 



