PLATE i 
A. —Stem-tumor of apple tree from West Virginia. Natural size. Photographed 
April 22, 1923. No crowngall organism could be isolated from these tumors. 
B. —Crowngall on apple stem produced by inoculating with Bad. tumefaciens 
(peach strain). Inoculated March 11, 1908. Photographed August 10, 1908; three- 
fourths natural size. 
C. —Old and young stem-tumors on Wagoner apple tree, Virginia; one-fifth natural 
size. • 
