SMITH S DISEASE OF AMARANTHS. 



149 



gas was formed. Its color on potato was at first pale yellow and then distinctly ochraceous 

 a color lying between ochraceous and ochre-yellow (Ridgway's plate v, 7 and 9), i. e., there 

 was much more buff in it than in 

 cultures of Bad. campestre. It was 

 cultivated at room temperatures 

 ranging from 18 to 24 C. The 

 substratum was soon stained a de- 

 cided gray (not brown), drab -gray 

 (Ridgway's plate 11, 13). I have a 

 note saying that several tubes of 

 potato inoculated with Bacterium 

 campestre the same day were not 

 grayed (fourth day). At the end of 

 25 days a little of the potato from 

 immediately under the thin layer of 

 bacteria blued litmus paper decid- 

 edly. On mashing old potato cul- 

 tures in iodine potassium-iodide 

 water there was a copious brown-pur- 

 ple reaction, showing that the starch 

 had been acted upon only a little. 



The organism grew on sugar- 

 beet cylinders, producing consider- 

 able yellow slime, but the culture 

 was dead at the end of 5 months. 



In its morphology, so far as examined, it closely resembled the ordinary forms of Bact. 

 hyacinth-i, being a short rod with rounded ends. No long chains, filaments or endospores 



were observed. 



Its general morphology and relation to 

 the tissues is shown in figures 65, 66, and 

 67. So far as I have been able to deter- 

 mine from an inspection of the microtome 

 sections the vessels are occupied (a small 

 number only in the material cut), the inter- 

 cellular spaces in the pith (frequently), and 

 also occasionally large pith-cells. The 

 latter have pits in their walls, and appar- 

 ently the bacteria have forced their way 

 through these thin places into the interior 

 of these cells. Surrounded by free cells 

 these bacterially occluded cells present a 

 striking appearance when stained deep red 

 with fuchsin. The bacteria were found fre- 

 quently in crystal-cells. I have observed 

 no bacteria in the cortex, which is made up 

 largely of eollenchyma. 

 Fig. 67. t 



Fig. 66.* 



*Fig. 66. Pith-cell of amaranth occupied by Bacterium amaranthi. Other similarly occupied pith-cells occur 

 and it is believed that the bacteria gained an entrance from the intercellular spaces by way of thin places in the wall 

 (pits), some of which are shown in the middle of the figure. Slide 450 B 5. 



|Fig. 67. Xylem vessels of amaranth stem occupied by Bacterium amaranthi. Also margin of a cavity. Slide 

 450 B 2, lower row, left-hand section. Drawn with Zeiss 2 mm. 1.30 n.a. apochromatie objective, No. 12 comp. ocular, 

 and Abbe camera. 



