70 CEOWN-GALL OF PLANTS. 



August 14, 1908: All the larger galls were removed. They are 

 now 2 inches in diameter. 



November 16, 1908: The remaining tumors have grown a great 

 deal and have partly decayed. 



April 2, 1910: The hard galls on tree No. 2 were photographed 

 (PI. XII, fig. 2), the tree repotted, and the galls wrapped in sphagnum 

 to see if roots would develop from them. The buds on the tree are 

 just opening. 



June 25, 1910: No roots have yet formed on peach gall growing 

 on apple under wet sphagnum, but the gall has begun to make new 

 growth in places. 



October 13, 1910: The sphagnum was removed and the galled 

 portion of the tree brought in and examined. A considerable area 

 of finely warted new tissue had formed and some parts of the gall 

 had given rise to small roots, but they were not of the hairy-root 

 type. 



The peach organism was recovered from this gall by means of 

 poured plates. 



Inoculations of May 10, 1908 (Brown). 



Thirteen seedling apple trees, ranging from 6 to 12 inches in height 

 and growing in pots in the greenhouse, were inoculated with the peach 

 gall organism as follows: Seven at the crown and also on the stem; 

 6 at the crowm only. Agar streak cultures 4 days old were used for the 

 inoculations. Four check plants were held. These were punctured 

 with a sterile needle on crown and stem. 



Result. — September 2, 1908: A gall 2 inches in diameter on the 

 stem of one tree; a gall one-half inch in diameter on the stem of 

 another tree. Galls had also formed at the crown of 3 other trees. 

 One of these was 1^ inches in diameter. Two of the trees inoculated 

 on stem and crown did not make any growth. Of the trees which 

 were inoculated at the crown only, 2 died and 4 did not make any 

 growth, consequently no tumors formed. In this experiment we 

 may claim 100 per cent of infections if we exclude the 8 trees which 

 did not grow. 



There were no galls on the check plants. 



Inoculations of May 22, 1908 (Townsend). 



Thirty-five apple seedlings (variety, Kansas) were inoculated by 

 needle puncture on the crown just above ground, using agar streak 

 cultures of peach organism 3 days old. 



Thirty-five trees of the same kind were punctured in the same way 

 with a sterile needle for control. 



Eighteen apple seedlings (variety, Virginia) were inoculated in the 

 same way. 



213 



