228 Bacteriological Department. [Bull. 161 



shave off foreign dirt from one bank. The measure is then 

 placed against this bank and held so that a hole is just two 

 inches below the surface. The sampler is then adjusted to 

 take, say, 1 cc. (see fig. 1). After sterilizing the steel sampler 

 in a blow-torch, with the right hand pass the point through 

 the hole in the measure and force it into the soil, turning it 

 once to free the outside from the soil. With the left hand 

 take the corresponding test-tube from the case. Withdraw, the 

 sampler, holding it between the first and second fingers of the 

 right hand, loosen the set-screw with the left, draw the plug 

 (of the test-tube) with the back of the third and fourth fingers 

 of the right hand, flame the mouth of the tube, then stroke the 

 sample with the outer rim of the mouth of the tube, thus ob- 

 taining as accurately as possible one cubic centimeter of soil. 

 Insert the sampler about one-half inch within the test-tube, 

 then place the thumb of the right hand upon the plunger-head 

 and force the sample into the test-tube. Withdraw the sampler, 

 replace the plug, and place the tube in the rack. 



The samples are then taken to the laboratory and each tube 

 receives 19 cc. of sterilized distilled water, after which it is 

 shaken until all the soil particles have separated. 



A millimeter loop of this soil suspension is placed in 10 cc. 

 of liquefied nutrient agar having a reaction of +1.5 to phenol- 

 pthalein, and the inoculated medium shaken and poured into 

 a Petri dish. The plate cultures were kept at a temperature 

 of about 23 degrees C. The colonies were counted at the ex- 

 piration of from twenty to twenty-four hours. 



