rathay's disease of orchard grass. 



159 



able to grow it in +15 beef peptone bouillon. At the end of 16 days small circular yellow 

 colonies appeared on some of the agar plates, and transfers grew fairly well on the surface 



of agar stab-cultures. It also grew 

 slowly on agar-stabs when intro- 

 duced along with the white organ- 

 ism mentioned below. It did not 

 grow readily in nitrate bouillon. 



In the plant it is quite inclined 

 to be associated with a white lique- 

 fying organism which grows as a 

 very short rod usually in pairs or 

 fours with a plain constriction. 

 This white organism grows in agar, 

 where it is motile in early stages of 

 growth on the margin of the colo- 

 nies. It was not clearly motile 

 when taken from a 5-day potato 

 culture, and here T's and Y's were 

 seen. It stains by Gram. 



The yellow organism is alcohol 

 fast, but not acid fast. It is Gram 

 positive, and during the viscid stage 



Fig. 7 le.f 



Fig. 7IA.** 



Fig 71/4 



on potato possesses a capsule. The yellow slime from a 7-day culture on potato was 

 feebly alkaline to neutral litmus paper. The color on potato resembles that of Aplano- 

 bactcr michiganense (pi. 11, figs. 8, 9) and the substratum is grayed. 



*Fig. 7i<f. Cross-section of stern similar to those shown in fig. 71a. At B. B are dense bacterial masses separat- 

 ing the immature leaves which are still nearly free from infection. At X bacteria may be seen occupying the sub- 

 stomatic chamber and intercellular spaces. Slide 940 F 5. 



|Fig. -jie. Cross-section of a leaf of Dactylis glomeruli, showing occupation of some of the intercellular spaces 

 by A planobacter rathayi. Section of material received from F. K01pin Ravn, of Denmark, summer of 1913. Slide 940 G 2. 



JFig. 71/. Detail of bacterial occupation of the intercellular spaces of leaf of Dactylis glomerata. From the 

 same material as fig. -jie. Figs. 71c and 71/ drawn by Katherine Bryan. 



Fig. 7ig. Bacteria from a 20-day agar plate culture of Rathay's organism stained by Ribbert's capsule stain. 

 Dec. 29, 1913. 



**Fig. 71A. A detail from fig. 71c A, showing one inner epidermal leaf-cell with some of the adherent bacterial 

 layer. Drawn from a free-hand section by Katherine Bryan. The fine granules are an effort on the part of the artist 

 to represent bacteria out of focus. 



