ON INTESTINAL ORGANISMS. 



59 



there was a larger number of organisms to begin with ; while the 

 colon bacilli multiplied considerably in the filtered water still there 

 was a very marked inhibiting action. At first I was inclined to 

 attribute this diminution in the number of the organisms to minute 

 traces of copper in the flasks, but subsequent experiments showed 

 that this was not the case. I was, then, inclined to attribute 

 these rather anomalous results to the presence of extremely small 

 quantities of copper dissolved by the water in its necessarily slow 

 passage through the copper spigot to which the filter was attached. 

 In order to test further the validity of this assumption another 

 series of experiments was conducted using (a) tap water, (/;) water 

 filtered through a stone filter, 1 and (V) water filtered through a 

 Berkefeld filter. The water in each case was sterilized in an auto- 

 clave at a temperature of no° C. for 30 minutes, and iS- to 24- 

 hour cultures of typhoid and colon bacilli were respectively added 

 to the samples of water at the ordinary temperature. The results 

 are summarized as follows : 



Table III. — Experiments with Bacillus 

 Water. 



coli and B. typhi in Filtered 



Stone 

 Filtered 

 Water. 



Berkefeld 

 Filtered 

 Water. 



Bacillus typhi. 



^ Stone ! Berkefeld 



Tap Filtered Filtered 



Water. Water. Water. 



At time of adding 



culture. 

 At end of 2 hours. 



" " 4 « 



" " 6 " 



" " 8 " 



« "24 " 



« "48 " 



" "7 days. 



" " 14 « 



" " 21 " 



" "3° " 

 « "60 " 



5,040 



6,426 

 8,505 



6,930 



16,065 



315,000 



630,000 



10,611 



18,270 



24,570 



28,350 



77,175 



630,000 



1,000,000 



7,875 



10,269 



6,600 



5,500 j 2,714 



5,040 



2,646 



3,654 



150,000 



200,000 



,512 1,764 



2,520 No or- 

 ganisms. 



250 

 150 

 38 

 39 



1,289,333 



1,505,700 



599,333 , 80,770 



900,000 

 730,800 



1,260,000 

 945,000 



94,500 j No or- 

 ganisms. 

 t49,33l I " 



2,930 

 3,829 

 1,820 

 9,000 



43 

 No or- 

 ganisms. 



1 In the preliminary experiments with samples of water that had been filtered 

 through a stone filter or a Jewett filter, it was found that there was a similar in- 

 hibiting action on the organisms to that of water from the Berkefeld filter. 

 This action was supposed to be due to the influence of the copper in the spigot 

 attached to the receiver of the filter, and was overcome by removing the spigot 

 and using a rubber stopper fitted with a glass tube. 



