312 



Profs. Percy Frankland and Marshall Ward. 



"by exposure to the rays of a winter sun (November and December), at 

 temperatures so low that no question of heat can come into considera- 

 tion ; moreover, the experiments prove that the bacteria spores are 

 really killed, and not merely retarded (p. 307). 



15. That we have here an essential part of the explanation of 

 numerous phenomena cannot be doubted, e.g., the purity of shallow 

 running waters, and the steady diminution of bacteria from our rivers, 

 lakes, &c. ; while, conversely, the suspension of solid particles, ren- 

 dering water turbid, may obviously react on their bacterial life by 

 intercepting the sun's rays. 



16. These experiments also suggest how necessary it is to conduct 

 all cultures of such bacteria in the dark ; and bring vividly before ur 

 the importance of direct sunlight in our streets and dwellings, &c, and 

 in numerous circumstances of life. 



1 7. In no case have we succeeded in showing that Bacillus anthracis 

 multiplies to any considerable extent in the form of vegetative 

 bacilli in the above waters, unless appreciable quantities of organic 

 food materials are added and the temperature is raised to above 

 12° C. So far as we can decide, the bacilli either die off in the 

 course of the first day or two, or, if the conditions are favourable, 

 they form spores (pp. 272 — 273). I regard this question as to the 

 power of the bacilli to multiply or form spores in the water as the 

 most important from a hygienic point of view ; unfortunately it is 

 also by far the most difficult one to answer. 



18. Aeration and consequent disturbance of the water contain- 

 ing anthrax does not destroy nor appreciably affect the latter 

 (pp. 299 — 302). Nor does the presence of ordinary green Algae in 

 the standing water seem to affect it, or, at any rate, not more than 

 can be explained by the diffused light necessary for the Algae 

 (pp. 278—283). 



19. Experiments prove that anthrax by no means succumbs easily, 

 if at all, in the struggle for existence with Bacillus jluorescens liqne- 

 faciens, one of the commonest of the Thames bacteria, and remarkable 

 for its aerobism and liquefying powers (pp. 290 — 298). 



20. Whether the result will be the same with other bacteria 

 selected for antagonism remains to be shown ; several other Thames 

 bacteria have been isolated, and are being studied in detail to the 

 end that their effects may be tested. 



