Report on the Bacteriology of Water. 



347 



a degree. Moreover, the temperature of the water-cell also rose con- 

 siderably above that of the CaS0 4 cell. Why, then, did the spores 

 exposed to light through water not germinate out more rapidly ? 

 Those in the dark did ! though not so rapidly as those behind 

 bichromate. 



It seems to me the only possible explanation is that behind the 

 bichromate screen we have the effects of a higher temperature due 

 to the transmitted infra-red rays superposed on the beneficial 

 effects of the absence of the inhibiting blue rays, which the bichro- 

 mate cuts off. 



I think the absorbed infra-red rays must be effective in some way, 

 or else the dark culture ought to have germinated as readily. If this 

 is so, it raises an extremely interesting and important question as to 

 the sources of energy available from without to these organisms, and 

 may possibly help to throw light on many obscui'e points connected 

 with the extraordinary capacity for work which they show. 



But we cannot explain the striking difference between the water 

 and the bichromate action as merely due to temperature. Indeed 

 none of the results would accord with that, for it was merely a ques- 



Water. 



Average. 



Extremes. 



Mean. 



Com- 

 monest. 



No germination 



None ger.ninated all dead. 



Dark. 



Average. 



Extremes. 



Mean. 



Com- 

 monest. 



5-6 (10) 



6-6 (10) 



9 -9 (10) 



31-5 (11) 



72-0(12) 36112 



No germination. 



4-56-75 



59 

 513 -5 



18-67-5 



5-75 



7-0 



9 25 



42-75 



74-0 



4-5 



5-0 



9-0 



22-5 



4559 



Dense meshwork of filaments over 1000 /u 

 long. 



Curves 36-41. 

 2 B 2 



