STEWART'S DISEASE OP SWEET CORN (MAIZE). 



129 



Here the overmastering influence was the lack of room to make a vigorous juicy growth 

 Many of the stalks were brittle as pipe-stems when cut. 



SERIES XXV. 1912. 



In the spring of 1912, Lucia McCulloch, of my laboratory, inoculated sweet corn and 

 field corn in the hot-house by spraying on a water suspension of Bact. stewarti when the 

 plants were about a foot high. Soon after, they were set out on the grounds of the U. S. 

 Department of Agriculture, where they grew well and showed but slight signs of disease. 



When cut in September the field corn was free 

 from disease. Of the sweet corn about one-half 

 of the stems were infected, but most of them 

 only slightly. Of the whole number (about 50) 

 only 5 or 6 were badly diseased. The season was 



Fig. 54.* 



Fig. 55. f 



a growing one and the organism was infectious. The feeble results, therefore, are to be 

 attributed, I believe, either to resistance on the part of the variety used or to the lateness 

 of the inoculation, *". e., after the plants had passed out of the seedling stage. 



*Fic. 54. Cross-section of the base of a sweet-corn kernel, showing a single spiral vessel filled with Bacterium 

 itewarli. the result of an inoculation made about 2 months earlier by placing a trace of a pure culture on the tips of the 

 leaves of the seedling plant. Material fixed in strong alcohol, embedded in paraffin, sectioned on the microtome, 

 stained with carbol-fuchsin, differentiated in 50 per cent alcohol, and mounted in Canada balsam. Figure drawn 

 under the microscope with the aid of an Abbe camera. Slide 235 A 8. For orientation see fig. 47. 



tKio. 55. Cross-section of internodal bundle of a sweet-corn stem showing Bacterium stewarti occupying a single 

 vessel. Material obtained on Long Island. New York, July 16, 1902, fixed in 95 per cent alcohol, embedded in paraffin, 

 sectioned on the microtome, and stained with carbol-fuchsin. Slide 249 C 2. 



