28 APPLIED BACTERIOLOGY FOR NURSES 



that we have such a culture; let us now consider the 

 methods by which we continue to grow the same. 

 Our first step is to plant the bacteria either in a fluid 

 culture-medium, such as beef -broth, milk, etc., or on the 



Fig. 9. Platinum wires for bacteriologic use. 



surface of a solid medium, such as gelatin, agar, solidi- 

 fied blood-serum, potato, etc. It is obvious that these 

 culture-media must be absolutely free from other germs, 

 i. e., they must be perfectly sterile. In planting the 



Fig. 10. Method of holding tubes during inoculation (McFarland). 



culture, we have at hand the tube containing our original 

 pure culture and a tube of the sterile medium, e. g., 

 sterile broth, closed at the top with a cotton plug. All 

 we need to do is to transfer a little loopful of culture by 



