i 9 i6] RIGG—SOIL TOXIXS 303 



the box were of glass, all articles inside of the box could be seen 

 readily by the operator. 



The entire inside of the box, including the side of the gloves 

 and sleeves exposed to the air of the box, and the outside of all 

 flasks and other articles placed in the box, were treated thoroughly 

 with a 15 per cent solution of glycerine saturated with carbolic 

 acid. All of the cultures prepared were thus more or less exposed 

 to carbolic acid fumes. This solution was applied by means of a 

 sponge attached to a short stick. It was found that flasks and 

 dishes stuck to the paint treated with this mixture, so that a false 

 bottom of glass was placed in the box. The stoppers of the steri- 

 lized flasks (including 2 of sterile water) were flamed, and the flasks 

 placed in the box. Four tall stenders with ground glass covers 

 were sterilized in an oven for 5 hours at 120 C, and placed in the 

 box. A bottle of N/300 AgNo 3 was also placed in the box, as 

 were also a pair of 10-inch brass forceps and a waste jar containing 

 a little of the glycerine carbolic acid solution. Everything in the 

 box having been treated with the antiseptic solution, the cover of 

 one of the stenders was removed and dry corn placed in the stender 

 and the cover quickly replaced. In selecting corn for this purpose, 

 care had been taken to secure smooth kernels that would offer little 

 opportunity for the lodgment of air bubbles in the dent or elsewhere. 



The box now remained closed over night, to allow any organisms 

 in the air to settle to the bottom of the box and be held by the 

 glycerine solution. In the morning the operator thrust his hands 

 into the gloves, poured AgNO, on the seeds, left it on for 1 minute, 

 poured it off into the waste jar, and then washed the seeds in several 

 changes of sterile water, finally allowing them to soak in it for 

 several hours, and rinsing them again. The tips of the forceps 

 now were washed thoroughly in the sterile water and the transfer 

 of the seeds was made. In some cultures the seeds were thrust 

 down into the sand by means of these forceps, and in some cases 

 they were left on the surface. After 2 or 3 cultures had been made, 

 the forceps were placed in the antiseptic solution for a few minutes 

 and again rinsed in sterile water. After the cultures were prepared, 

 they were removed from the box and placed near a window in the 

 laboratorv. 



