428 Bulletin 315 



receiving a threaded cap that was made to fit very snugly. The tube, 

 being closed by means of the cotton plug and the cap, was sterilized in a 

 hot air steriHzer for one hour at 140° C. The tube was attached to the 

 handle on am\dng in the field, and after the very topmost layer of soil 

 (approximately one fourth inch deep) had been removed, the cap was 

 removed and the tube inserted into the soil by a rotary motion. The 

 soil being under cultivation, the tube could be inserted to a depth of 

 about sbc or seven inches without much difficulty. The tube was now 

 extracted from the soil and the cap again attached. The main objection 

 to taking the sample by this method lies in the resistance offered by the 

 tube to the entrance of the soil. When the tube is inserted into the soil 

 seven inches, the soil to this depth is not sampled owing to compression. 



In December, 19 10, the soil had become frozen so that samples could 

 not be taken by using the above-mentioned tube. The "following method 

 was therefore resorted to during December, January, February, and 

 March: A pit approximately ten inches wide, two feet long, and one foot 

 deep was dug. With a sterile knife (flamed over an alcohol lamp) the 

 soil was removed from the edge of the pit, where it was desired to obtain 

 the samples. After removal of this soil, the knife was again sterilized 

 and the sample was taken at the desired depth, one to three inches, and 

 removed as quickly as possible to a sterile wide-mouthed glass bottle, after 

 removal of the cotton plug. Immediately following the introduction of 

 the soil into the bottle, the cotton plug was again replaced. A second 

 sample was taken directly below the first at a depth of four to five inches, 

 and again a third at a depth of six to eight inches. Precautions were 

 always observed to avoid as much as possible any contamination. 



In May, 191 1, laboratory equipment as complete as possible was shipped 

 to Atlanta, N. Y., where the summer's field work was to be carried out. 

 Having only a modified Arnold sterilizer at command, the method of 

 taking samples necessarily had to be altered. 



Samples J, K, L, M, and N were taken after the following manner: 

 Three Erlenmeyer flasks, each containing 50 cc. of distilled water and 

 carefully plugged with cotton, were sterilized in the modified Arnold 

 sterilizer for thirty minutes at 97° to 99° C. on three consecutive days. 

 After sterilization they were taken into the potato field where the samples 

 were to be collected. A pit was dug similar to that described above in the 

 winter collection of samples. At each of the depths two, four, and six 

 inches, a small quantity of the soil (approximately one fifth gram) was 

 taken on the end of a sterile scalpel (flamed in an alcohol lamp) and intro- 

 duced into each of the Erlenmeyer flasks. Every precaution was observed 

 to avoid contamination, as previously mentioned. The flasks containing 

 the inoculated water were now taken to the laboratory, where they 



