GRASSES OF IOWA. 285 



was quite dry, and there was at no time subsequent to the 

 planting any superfluous water in the area described. The 

 seed germinated and the young corn grew satisfactorily until 

 after the second plowing, when the plants were more than six 

 inches high; then the newly-tilled spot showed, by the change 

 in the appearance of the corn, in a very definite manner, to the 

 very furrow on the margins, a distinct difference from the rest 

 of the field. The corn ceased growing, became yellow and 

 unusually slender, then for the most part died." After corn 

 has tasseled the disease may be found widely scattered through- 

 out the field, affecting a stalk here and there. The young 

 plants usually show a yellowish cast; the roots are also affected; 

 a stalk split lengthwise shows that the inner middle portion of 

 the stem is of a dark color; on the surface of the leaf and stem 

 brownish, corroded spots may be seen — in some cases these 

 spots are covered with semi-transparent gelatinous material; 

 the ears and husks are affected occasionally. 



Moore states that h3 had no difficulty in obtaining nearly 

 pure cultures of this organism from the first stage of the 

 disease. The dwarfed corn resulting from the attacks of 

 bacteria are quite rare. Moore confirms the results of Burrill 

 that this organism occurs ia a large number of cornstalks and 

 is abundant in the gelatinous flakes. Burrill 's experiments in 

 showing its pathogenic nature were not successful, but later an 

 application of a pure culture applied to the inside of the leaf 

 sheath, without puncture, gave positive results. 



Moore says: " Whether these organisms are of themselves 

 able to gain entrance into the parenchy-matous tissue of the 

 leaf sheaths after being lodged by various agencies against 

 the exterior of the plant, or whether they are inoculated into 

 the tissues by means of insects or injuries to the epidermis 

 otherwise inflicted is not determined. " 



This organism is therefore parasitic, and should be classed 

 with the faculative parasites. It has been shown that in addi- 

 tion to Bacillus doaceae other saprophytic organisms occur, and 

 that these may produce lesions. This is not inconsistent with 

 the work done by Russell," who has shown that a large number 

 of bacteria, mostly saprophytes, can live for a certain period 

 and spread as parasites. 



•Bacteria in their relation to vegetable tissue. Rep. Johns Hopkins Univ. Hospi- 

 tal 3: 223. 1893. 



