214 Profs. P. F. FranMand and Marshall Ward. 



In a second paper,* Karlinski goes more deeply into the question 

 of the maintenance of the typhoid bacillus in a natural water, work- 

 ing in the open in order to avoid the errors due to confined samples 

 in the laboratory. The temperature, chemical constitution, and 

 bacterial contents of the water were examined, and the well was then 

 infected with a bouillon culture of typhoid germs. 



Daily examination of the contents, continually stirred to prevent 

 precipitation, showed a rapid increase of the normal water bacteria, 

 and a corresponding decrease of the typhoid bacilli, till none of th e 

 latter remained after fourteen days. 



The chemical constitution of the water, examined daily, also re- 

 stored itself during the fourteen days through which the infection 

 lasted. Other experiments confirmed these results. 



§ IV". Summary and Conclusions. 



If we now try to put together the results of the various investiga- 

 tions referred to, it is evident that the inquiry into the vitality of 

 micro-organisms in ordinary waters is by no means to be carried out 

 merely by putting such germs into a given water, leaving them there 

 for a time, and simply determining their relative increase or decrease 

 during a given period. 



The first fact to be firmly grasped is that water, as met with in 

 actual life, is a very variable medium indeed ; and that even when it 

 is admitted that such rough, distinctions as are implied by the names 

 river water, spring and well water, distilled water, soft and hard 

 water, and so on, classify the subject but imperfectly, the matter 

 is by no means ended. Not only are no two river waters alike in 

 constitution, but probably no two samples of distilled water are abso- 

 lutely so when the original water has been taken from different 

 sources in the first instance. 



The second great fact to be clearly apprehended is that a Schizo- 

 mycete is not only a very minute organism, but that it requires 

 correspondingly minute traces of food materials for its nutrition : 

 consequently there is less cause for surprise than is sometimes ex- 

 pressed at the existence of such large numbers of these micro- 

 organisms in a natural water which has passed over the soil in con- 

 tact with the atmosphere, and attained an ordinary temperature. 



A less obvious truth — but one that must be insisted upon — is that 

 a Schizomycete is an extremely delicate organism, simply because it 

 is a living being, and therefore its reactions to a medium such as an 

 ordinary water are far more delicate and complex than those of the 

 usual chemical reagents : furthermore, and this is one of the most 



* "TJeber das Verhalten des Typhus-bacillus im Bruimenwasser " ('Arch. f. 

 Hyg.,' vol. 9, 1889, p. 432). 



