72 LABORATORY BACTERIOLOGY 



EXERCISE XXIII 



A STUDY OF BACTERIA IN WATER 



106. It is important to know something of the bacterial con- 

 tents of water as it is found in wells and streams, and to com- 

 pare the bacteria ordinarily found in water with those present 

 in freshly drawn milk. It will be observed that the normal 

 bacterial flora of water and of milk are quite different. 



REFERENCES. Percy and G. C. Frankland, Micro-organisms 

 in Water. Clark and Gage, 34th Annual Report Massachusetts 

 State Board of Health. Jordan, The kinds of bacteria found 

 in river water, The Journal of Hygiene, Vol. Ill, No. i (1903). 



107. Work for this exercise. Carefully examine and describe 

 the cultures made from the colonies on the milk plates in the 

 last exercise. 



Examine and describe the colonies on the plate cultures 

 made from water. Determine the number of colonies and 

 approximately the number of each kind of colony on the 

 plate. 



Examine microscopically the bacteria from one of each 

 kind of colony and determine the genus. 



Inoculate a tube of milk and one of gelatin from each of 

 three different colonies, if there are as many. In later exer- 

 cises examine these cultures and compare them with those 

 made from colonies of milk bacteria. 



Examine and describe the cultures of B. prodigiosus. 



Inoculate groups of media A and B from a culture of Ps. 

 fluorescens liquefaciens furnished. 



