226 



Bacteriological Department. 



[Bull. 161 



method of collecting samples is followed with uniformity 

 throughout the work. 



FIG. 1. Soil Sampler. 



OBTAINING SAMPLES, AND BACTERIOLOGICAL TECHNIQUE. 



The field outfit used in the work consisted of a small steel 

 soil sampler, a spade, a measure, a sample case and a gasoline 

 blow-torch. The soil sampler (fig. 1) is made of steel and 

 consists of a steel tube seven centimeters long with an inside 

 diameter of three-eighths inch and an outside diameter of 

 seven-sixteenths inch. The plunger (D), with a plunger-rod 

 one-eighth inch in diameter, is connected with the cylinder 

 through a one-eighth inch hole (B), and is clamped and held 

 at the desired place by the set-screw (D). The plunger-head 

 (A) is just a working fit inside the cylinder. The plunger- 

 rod (D) is graduated so that the plunger-head allows 1, 2, 3 or 

 4 cc. of soil to be taken, as desired. 



The Sample Case. The sample case (figs. 2 and 3) is 24 

 inches long, 18 inches high, and 12 inches wide. A lid, to 

 which is attached the handle, covers the entire top. This is 

 raised and the two catches at either end are released, which 

 allows the case to open. On each side of the case, running the 

 entire length, are three perforated shelves for holding test- 

 tubes. The top shelf is two inches wide and holds 20 test- 

 tubes. The second shelf is four inches wide and holds 20 

 test-tubes, while the lower shelf is six inches wide and holds 

 the same number of tubes. The entire case holds 120 test- 

 tubes, and when full weighs 7.45 kilograms. 



The reason for having the shelves of different widths can 

 be seen in the cut, as it allows the handling of one row of 

 test-tubes without disturbing the others. The test-tube per- 

 forations are numbered to correspond with the depth of the 

 sample and number of the plot, so that when a sample is taken 

 the corresponding test-tube can be filled and replaced, thus 



