102 EXPERIMENTAL DAIRY BACTERIOLOGY 



It is probable that water which would be pronounced good 

 as the result of a sanitary analysis would be desirable for use 

 in the dairy.. For the methods of making a complete bacterio- 

 logical analysis of water, the student is referred to books on 

 water analysis. 



The quality of the water may be determined roughly by 

 the inoculation of dextrose-fermentation tubes with 0.1, 1, 

 and 10 cc. of the water. Gas production is indicative of pol- 

 lution with organic matter, a condition which should not ob- 

 tain in a creamery well. The results obtained with the series 

 of fermentation tubes give some idea of the number of gas- 

 producing bacteria present. 



Gelatin plates inoculated with varying quantities of the 

 water (0.1, 0.5, and 1 cc.) should show few liquefying bac- 

 teria, especially of the fluorescent type (B. fluorescens lique- 

 faciens). 



Flasks of sterile milk (100 cc.) should be inoculated with 

 10 cc. of the water, and the nature of the curd and the flavor 

 noted. 



Exercise. Each student will test by means of dextrose-fermenta- 

 tion tubes, gelatin plates, and milk, five samples of water representing 

 supposedly good waters and also those polluted with varying amounts 

 of surface drainage. 



