EXPERIMENTS WITH THE ALFALFA ORGANISM. 59 



Result. — August 20, 1909: No indications of galls forming or of 

 hairy-root outgrowths. 



December 2, 1909: Twelve plants had formed crown-galls. The 

 checks were free. 



As it was always necessary to knock the plants from the pots, 

 wash and examine the roots, they were more or less injured and set 

 back in their development by this procedure. Possibly the seedlings 

 were too young for best results. 



Inoculations op September 7, 1909 (Brown). 



Inoculated 3 pots of 1 -year-old alfalfa plants with pure cultures 3 

 days old and 6 pots of young plants having taproots 3 mm. in diameter. 

 The roots in both sets were inoculated at the crown. There were 

 4 plants in each pot, making 36 plants in all. Eight plants (2 pots) 

 were held as checks. 



Result. — December 2, 1909: Examined the plants and found one 

 pot (4 plants) with very distinct and numerous galls on the roots; 

 and two other pots (8 plants) containing plants with less numerous 

 galls on the roots, making in all 12 plants with galls. Tiny, fine roots 

 projected from these galls. The checks were free. Plates were 

 poured from one of these galls to reisolate the organism. Some of 

 these galls were photographed (PI. XVI, fig. 2a), some preserved in 

 alcohol, and some given to Mr. Kellerman to preserve. 



First Inoculations of December 8, 1909 (Brown). 



Gall colonies grew on the plates poured December 2 (see preceding) 

 and inoculations were made into young seedling alfalfa plants to 

 check the cultures. 



Result. — May 11, 1910: All of the inoculated plants now show galls. 



Second Inoculations of December 8, 1909 (Brown). 



The plants used were several years old and in poor condition. The 

 culture used was a subculture from a colony on a poured plate of 

 December 2, 1909. 



Result.— ^l^j 11, 1910: No galls. 



ALFALFA ON PEACH. 



Inoculations op January 27 and February 1, 1910 (Brown). 



On January 27 six peach trees, which had just started to send out 

 leaves, were inoculated at the crown by needle pricks with 1 -day-old 

 cultures of the alfalfa gall organism (first isolation). The trees were 

 in pots in the greenhouse. 



On February 1 eight young peach trees of the same lot as those 

 inoculated January 27 were inoculated with 1-day-old cultures of the 



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