82 CEOWN-GALL OF PLANTS. 



than the average cork layer were also removed. Once or twice the 

 denuded surface was also rubbed gently under the dismfectant with 

 the finger tip. Great care was taken not to wound the deeper tissues. 

 At the end of the 20 minutes the beet was rinsed quickly in a large 

 volume of sterile water, then wrapped in sterile paper and put away 

 over night. Only that mercuric chloride lying on the surface was 

 washed away, not that absorbed into the superficial layers of the 

 tumor. 



On November 16 washed pure white sand (for grinding the tissue) 

 was dry heated in the oven one hour at 240° to 250° C. The Wedg- 

 wood mortar and glass pestle and the distilled water used were auto- 

 claved for one-half hour at 110° C. As checks on the sterility of the 

 water, the surface of the gall, and the sand and mortar used in grinding 

 the tumor, three plates were poured. 



Toward noon (about 20 hours after treatment) the beet was 

 uncovered, the thin dead surface now covering the tumor was removed 

 with sterile scalpels and thrown into 10 c. c. bouillon. The volume 

 of the gall was now measured in sterile water. It displaced 8 c. c. of 

 water. A cube of the white flesh, approximately 4 by 4 by 4 mm., 

 was cut out and thrown into 10 c. c. bouillon to duplicate Reinelt's 

 experiment as nearly as possible (see later). The remainder was 

 thrown into the mortar, cut into small fragments with sterile cold 

 scalpels, several grams of the sand added, together with 40 c. c. of 

 sterile water, and the material then ground vigorously for 15 minutes, 

 i. e., until the beet was pulped and the fluid began to darken from 

 oxidation. The mortar was tilted and the mass allowed to settle for 

 10 minutes, after which 20 c. c. of the fluid was recovered by means of 

 sterile pipettes and put into sterile test tubes. All of this fluid was 

 then distributed into 10 c. c. volumes of nutrient +15 agar, using a 

 sterile pipette, and 68 Petri-dish plates were poured during the next 

 three hours as follows: 5 received 1 drop each; 10 received 2 drops 

 each; 5 received 3 drops each; 5 received 5 drops each; 5 received 

 10 drops each; and the remaining 38 received 0.5 c. c. each. The 

 work was done in a clean culture chamber. The agar was inoculated 

 and poured at 39° to 40° C. The three check plates gave the fol- 

 lowing results at the end of the seventh day: 



No. 1, inoculated with 1 c, c. from a tube of 10 c. c. bouillon in 

 which all the scrapings of the sterilized surface of the gall were 

 allowed to soak for an hour — nothing. 



No. 2, inoculated with 1 c. c. of washings from the dry heated 

 white sand — nothing. 



No. 3, inoculated with 1 c. c. of washings from the interior of the 

 autoclaved mortar before using it — 1 mold spore. 



213 



