118 



Neither was any effect of the bacteriopliages on cholera-vibriones 

 at all apparent. 



Tiiis result conld be expected, as it is known that from the 

 dejecta of fowls and iiorses a nearly always highly active liacterio- 

 pliage antibacteria dyseiiteriae can be isolated and the sniface- water 

 in and about Ijeyden is being constantly polluted on a large scale 

 by the excrements of a number of living beings, also by those of 

 horses and fowls. 



Anyhow this inquiry teaches ns that l)acteriophage occms in the 

 surface-water of Leyden. 



On the 2'' of June quantities of 5 Liters of various kinds of 

 Leydenwater were infected every time with two loopfuls of a 24- 

 hour-old cholera-culture. The infected water was placed in large 

 glass receptacles in diffuse daylight at room temperature (15°C.). 



On the 21*^' of June we examined two quanta of 25 c.c. of water; 

 in neither of those samples could cholei'avibriones he detected. 



Of every sample of 5 L. 25 c.c. was examined for bacteriophages 

 hy mixing the water with '/n of the volume of concentrated broth, 

 and inoculating the mixture with a loopful of an 18-lionr-old 

 cholera-culture. 



After an incubation of 24 hours at 37° C. the sample was exam- 

 ined in the usual way for bacteriophage anticholera-vibi'iones. The 

 result was negative. 



On the 24''i of June three flasks were filled each with 0,5 L. of 

 Rijnwater, in which, as our examination had proved, bacteriophage 

 antibacteria dysenteriae was present. 



Flask I was inoculated with the whole cholera-culture of a sloped 

 agar tube; flask II in the same manner with typhus-bacilli; and 

 flask III with Shiga-Kruse bacilli. 



The fluid of each of the three flasks became very tin-bid and 

 was placed at room-temperature in diffuse daylight. 



On the fifth of July the fluid of each of the three flasks became 

 lucid and was examined for bacteriophage in the ordinary way. In 

 all the flasks we found bacteriophage aniidy.'ienteriae, which was 

 present in the water already before the beginning of the experiment, 

 but in the typhns-flask not any bacteriophage antityphus wasfouiui, 

 no more than bacteriophage anticholera in the cholera-flask. 



The flask infected with Shiga did not become Incid sooner than 

 the one infected with typhus and cholera, which might have been 



