CHAPTER IV. 



CULTIVATION BY STROKE AND PONCTUEB, IN THE HANGING 

 DEOP, AND ON THE SLIDE. 



Aptee having, as described in the preceding chapter,- 

 isolated several kinds of bacteria by means of plate 

 cultivations, it becomes necessary to keep them per- 

 manently apart, if we wish to continue their obser- 

 vation for some considerable time. This would not be 

 the case if they remained for any length of time on 

 the plates. For quite apart from the fact that very 

 soon the gelatine would dry up, as a rule mould-fungi, 

 or bacteria, which cause the gelatine to liquefy rapidly, 

 make their appearance, having been either present in 

 the gelatine from the beginning, or having gained 

 access to it whilst the dish was opened, the result 

 being that very soon all the colonies would run into 

 one another. In order to avoid such a misfortune, the 

 separate colonies must be transferred with a sterilised 

 platinum wire into test-tubes, containing some nutrient 

 medium, each tube, of course, being inoculated from 

 only one colony; the so-called stroke and puncture 

 cultivations are those most commonly used. 



