188 



Profs. P. F. Frankland and Marshall Ward. 



of towns, &c, and statistical comparisons of their behaviour at 

 different seasons, their vitality when placed in special waters, and so 

 on, have come from Germany. Of late years it would be difficult to 

 say where most activity has been displayed, the establishment of the 

 Pasteur Institute in Paris having led to the inauguration of brilliant 

 and industrious researches into every aspect of the questions we are 

 concerned with. Even now, however, it is especially to the reports 

 of the public hygienic institutions of Germany that we must turn for 

 the more technical and systematic comparative researches into the 

 main question of our enquiry — the length of life enjoyed by specific 

 Schizomycetes when placed in arbitrarily selected waters. 



We propose to adopt the following plan of treatment in this 

 Report : — 



(1 .) To give some account of what species or forms are actually 

 known to occur in natural waters, of various kinds, whether as more 

 or less normal and constant inhabitants of such waters, or as casual 

 foreign intruders. Some of these are well known, others we know- 

 very little about, while yet others require careful examination before 

 we can accept them as autonomous. We also refer to a few remark- 

 able forms found in special kinds of water, or under peculiar con- 

 ditions, only. 



(2.) We propose to draw attention to some of the facts now 

 acquired, which throw light on the questions of the relations subsist- 

 ing between the bacterial contents of natural waters, such as those of 

 rivers, springs, wells, reservoirs, &c, and the air and soil of the 

 neighbourhood, because some of these facts are of great importance 

 as regards the presence and supply of pathogenic germs in such 

 waters. This leads naturally to the discussion of recent experimental 

 investigations into the effects of certain factors of the physical 

 environment, e.g., temperature, light, oxygen, &c, in modifying the 

 life-actions of such bacteria as we are concerned with, and so far as 

 such effects may be expected to affect the general problems at issue. 



(3.) The questions, What bacteria can live in such waters as we 

 refer to? Can they multiply and spread in them ? Can definitely chosen 

 pathogenic species live and multiply in selected waters ; and, if so, 

 how long can they maintain themselves ? These, and similar questions 

 relating to them, will be treated in detail as fully as the literature and 

 our own personal experience in these matters enable us to do. 



This will, we think, cover the ground of the history and literature 

 of the subject, and will clear the way for our proposals as to lines of 

 enquiry to be entered into forthwith, and as to the methods we intend 

 to put in practice in pursuing the question further. 



