Cultural Methods 255 



incubation ol Fungi, and small foci of contaminants, which might be dis- 

 regarded at first, arc soon found in such massive quantities that the) er 

 roneousl) impress one as being of pathogenic titer. 



Pus is transferred by moans of a sterile syringe or a flamed platinum 

 loop, it the lesion is open. The material should be plaeed near the center 

 of the agar slant. The month of the tube may be flamed over a Bunsen 

 burner after the cotton is taken Out, before and alter inoculation. We have 

 not found that this procedure reduces the incidence of contamination, so 

 we have discarded it as unnecessary and burdensome. 



Care should be taken that the cotton ping is not contaminated while 

 the inoculation is being made. For instance, it must never be laid down. 

 It should not be withdrawn until the material is on the blade of the knife 

 and is reinserted as soon as the inoculation has been completed. 



Contamination starting at the upper pole of the agar slant or away from 

 the line of inoculation usually has originated from the outside, while the 

 tube was open. If contaminating organisms appear near or in the lines of 

 inoculation, they have probably been carried into the tube in the substance 

 of the inoculum. 



To culture Actinomyces from material in which granules are present, 

 add a large volume of saline and shake. The granules settle. The super- 

 natant fluid is drawn off. The granules are washed a second time and are 

 then drawn up into a sterile pipet and transferred to the depth of the 

 anaerobic medium. 



