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 ])lood-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 



