ii8 



BACTERIOLOGY 



make a smear preparation from the colony and to stain with one 

 of the aniline dyes so as to determine the m!orphology of the 

 bacteria. The growths which take place in the tubes should con- 

 tain one and the same kind of bacteria. As seen under the micro- 

 scope these bacteria should have the same general form and 

 appearance as those seen in the colony from which they were 



Pig. 46. — Stab-culture. 

 A rubber stopper may 

 *be used to prevent drying, 

 see page 119. 



Pig. 47. — Smear-culture. 

 This tube shows the 

 rubber cap used to prevent 

 drying. 



derived. This will be the case, provided the colony has resulted 

 from the development of a single bacterium. 



A pure culture is a culture which contains only the descendants 

 of a single cell. 



Stock Cultures.^ — To maintain their vitality bacteria need to 

 be transplanted from one tube to another occasionally; the time 

 varies greatly with different species. Many bacteria grow on 

 culture-media with difficulty at the first inoculation, but having 



