Report on the Bacteriology of Water. 



351 



The following table (p. 352) summarises the result. 



All things considered, and especially the difficulties of measun'ng 

 the averages of the more advanced cultures, these three curves agiee 

 very well, and show clearly that neither the germination nor the sub- 

 sequent growth of the bacillus is in the least hurt by the heating and 

 drying of the spores. Indeed, it is difficult not to suspect that the 

 vigour of the organism is improved rather than injured by the treat- 

 ment.* 



Experiments with Groioing Filaments. 

 Three broth-drop cultures were started ; and placed at 20 22 C. 



Curves 42 45. 



in the dark at 9 A.M., where they remained until 2 P.M., when germi- 

 nation had begun in all. 



They were then distributed as follows : One remained in the 

 dark under the bell-jar covered with foil and paper ; a second was 

 over a bottle screen of water, tinged slightly blue with CuSO*, 

 and arranged so that no direct rays reached it the top being shaded 

 by a thick card ; while the third was exactly as the second, except 

 that its screen was of K. bichromate. The two cultures in the light 

 had each a dummy cell and thermometer rigged up exactly in the 

 same way, and these and thermometers by their side and in the bell- 

 jar gave the tempe)ratures of the air and cultures. 



The day was a brilliantly hot and sunny one, but with light cumulus 

 clouds floating slowly in the blue. 



At 2 P.M. I selected a germinated rodlet, well out, under each mi- 

 croscope, and kept it wider observation the whole period. This was 

 made feasible by placing the screens below the stage of the micro- 

 scope the upper surface of the light cultures being shaded by 



* Brefeld found that such was the case when the spores of B. subtilis were 

 heated to boiling (' Unters. ii. Schimmelpilze,' B. IV, 1881, p. 51). 



