A STUDY OF BACTERIA IN WATER 69 
EXERCISE XX 
A STUDY OF BACTERIA IN WATER 
102. 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. 
103. 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 each of bouillon, agar, and 
gelatin from each of 3 different colonies, if there are as many. 
In later exercises examine these cultures and compare them 
with those made from colonies of milk bacteria. 
Examine and describe the cultures of B. prodigiosus. 
Inoculate groups A and B of media from a culture of Py. 
fluorescens liguefaciens furnished. 
