120 



BACTERIA IN RELATION TO PLANT DISEASES. 



859 [Emerson's First Crop]. Very bad looking. 



Cases, 8; sound, o. 



860 [Cosmopolitan]. All stems dead, with dried tassels and brown leaves. 



Cases, 21; sound, 7. 



861 [Metropolitan]. A slightly better stand, but most of the plants show the external signs of the disease. 



Cases, 18; sound, 12. Some of these cases showed only one or two bundles affected. 



862 [Hys' Metropolitan]. Looks about like 861. Many plants show external signs of disease, but there is a better 



stand than in the first four or five rows. 

 Cases, 14; sound, 14. Of the diseased stems in this lot 5 or 6 had only one or two bundles diseased. 



863 [Crosby's Early], Looks diseased, but is a rather better stand than others. 



Cases, 15; sound, 15. Some of the cases only slightly diseased. 



A little of this seed corn remained undistributed in the hands of the Free Seed Distri- 

 bution officials of the Department of Agriculture. As soon, therefore, as possible after the 

 discovery of the above-mentioned facts respecting infection of the trial rows, i. <?., the same 

 summer, the writer procured a quantity of the corn and had it planted on another farm. 



Fig. 51. 



Fig. 52. t 



The place selected was an old field on the Arlington estate, one which certainly had not 

 been planted in maize since before the Civil War, i. e., for more than 40 years, and perhaps 

 never. This field is about a mile and a half from the trial plots just described, on the other 

 side of the Potomac River, and there was very little communication between the two farms, 

 i. e., the management used different teams and tools and another set of farm laborers. 

 Here, if anywhere, one might expect to get the uncomplicated effect of the seed, since we 



*Fig. 51. Surface of a corn-husk highly magnified, showing a single stoma with Bacterium stewarti oozing to the 

 surface. The conditions immediately under such a stoma are shown in figs, so and 52. Slide 477 B 1. From a plant 

 inoculated in the seedling stage. Collected Oct. 21, 1902, Potomac Flats. 



fFiG. 52. Surface view of husk of sweet-corn attacked by Bacterium stewarti. Surface slightly curved, so that the 

 microtome knife has removed the greater part of the epidermis (crinkly-walled cells) laying bare the deeper tissues; 

 R, remnant of epidermis; Se, sub-epidermal tissue; Sc, sclerenchyma strand; St, remnants of stomata, about all that is 

 left of the three upper ones being a portion of the mother cell on the left side (see figs. 50 and 51 for orientation); Sst, 

 substomatic chambers filled with bacteria. Plant inoculated in August in the seedling stage by placing bacteria on 

 the tips of the leaves. Collected October 21, 1902, from Potomac Flats. Slide 477 A 8, stained with carbol fuchsin. 



