EXPERIMENTS WITH THE DAISY ORGANISM. 47 



growing well and all were free from natural tumors. The soil was 

 removed from one side of the plant, leaving about 1 inch of the root 

 exposed. This was rubbed with clean cotton wet with filtered 

 water and then inoculated. A large quantity of the milky fluid from 

 the slant agar cultures to which sterile water had been added was 

 put on the clean surface, 10 needle pricks about one-fourth inch deep 

 made through it, and more of the bacterial fluid put on. Six rapidly 

 growing daisies (from cuttings) were inoculated near the tip of the 

 stem, as checks on the virulence of the cultures. 



Result. — December 4, 1907: Some of the sugar beets were examined 

 carefully, and tumors found on all examined. The tumors were as 

 large as small peas (16 days). Quite a number showed as many 

 tumors as there were needle pricks, i. e., 5 or 6. All of the daisy 

 plants inoculated as checks showed tumors. 



January 29, 1908: All of the 36 beets developed tumors in the 

 pricked area. One plant attacked by nematodes (none of the others 

 were) also developed a second bacterial tumor about half an inch in 

 diameter near the basal part of the root. The other 35 plants were 

 attacked only where inoculated. 



Miss M. L. Shorey isolated oxidases and peroxidases (black sub- 

 stances) from these tumors. These were copiously inoculated into 

 the roots of numerous sound sugar beets, but no growths appeared. 



Inoculations of June 11, 1908 (Smith). 



Five sugar beets were inoculated with the daisy organism after 

 passing it through oleander (with production of tumors) and plating 

 it out again. 



Result. — August 10, 1908: Every one of the 5 plants has a tumor 

 at the place inoculated and not elsewhere. 



Inoculations op December 4, 1909 (Brown). 



Eight young sugar beets were inoculated with 2-day-old agar cul- 

 tures of the daisy organism just plated from a gall; the cultures used 

 were the first subcultures made. 



Result. — December 21, 1909: No galls had formed. The soil was 

 very cold and the temperature constantly low in the greenhouse. 



April 4, 1910: Galls had formed on each one of the 8 inoculated 

 sugar beets (PI. VIII). Some of these galls were 5 inches across. 



Remarks. — Out of a total of 85 sugar beets inoculated (5 experi- 

 ments) 83 contracted the disease and 82 of them only at the point 

 of inoculation. In 4 of the 5 experiments 100 per cent of the inocu- 

 lated plants contracted the disease, pure cultures being used. Numer- 

 ous uninoculated beets in the same houses remained entirely free 

 from the disease. 



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