52 BACTERIOLOGY FOR NURSES 



A tube of media in which bacteria are growing is spoken of as 

 a " culture." When only one species is present it is said to be a 

 " pure culture." If a small portion of an already existing growth 

 is transferred to a tube of fresh medium the resulting culture is 

 spoken of as a " transplant " or " subculture." To transfer 

 bacteria from one tube to another a platinum wire or loop is used. 



It should be thin 

 yet sufficiently stiff 

 and about two and 

 a half inches long. 



FIG. 16. Platinum Wire and Loop. r j g ftt _ 



tached to an aluminum holder or fused into the end of a glass rod 

 about seven or eight inches long. For making stab cultures or 

 for " fishing " a straight " needle " or wire is used ; for transfer- 

 ring growth from a fluid medium a wire turned at the end to form 

 a loop is employed (Fig. 16). The platinum needle or loop should 

 always be sterilized in the flame of a Bunsen burner immediately 

 before and after using. 



A subculture is made as follows : The culture and the tube 

 to be inoculated are held in a slanting position between the thumb 

 and the first and second fingers of the left hand ; the plugs are 

 gently twisted around once or twice 

 to make sure they are not sticking 

 to the tubes and if they have been 

 exposed to dust they should be 

 slightly singed in the gas flame. 

 The platinum wire, held between 

 the thumb and the first and second 



...... . FIG. 17. Method of Inoculating. 



fingers ot the right hand, somewhat 



in the manner of holding a pen, is sterilized by heating red hot in 

 a flame. The plugs are then removed, one is grasped between 

 the middle and third fingers and the other between the third and 

 fourth fingers. When cool enough the wire is carefully passed into 

 the culture tube and without touching the side a small amount of 

 bacterial growth is removed and immediately transferred to the 

 tube which is to be inoculated (Fig. 17). If the tube contains 



