45 



tion of the scape with the plateau, a larger number of bundles and more 

 scales were affected. The flattened side of this bulb (upper part of figure) 

 is where a daughter bulb pressed against it (see text, page 29). 

 Fig. 6. One scale removed from the bulb of plant No. 63 (fig. 5) and photographed 

 • by itself, to show the course of the disease in the vascular bundles. The 

 parenchymatic tissue between these yellow bundles was sound. 

 Fig. 7. Scape of plant No. 79, inoculated February 16 in the blossoms. Painted by 

 F. A. Walpole, March 5. The infection proceeded apparently from one 

 flower. 

 Fig. 8. (a) Ordinary form of bacterial rods found in the diseased bulbs. These 

 were taken from the daughter bulb mentioned on page 18, and were stained 

 two minutes in a saturated watery solution of gentian violet. X 1,000. (b) 

 Ordinary form of rods from an alkaline beef-broth culture nine days old. 

 Stained ten minutes in a saturated watery solution of Grubler's basic fuch- 

 sin. X 1 ,000. (c) Two long rods from a 30 per cent cane sugar agar thirty- 

 eight days old. No segments or septa visible. Van Ermengem"s nitrate of 

 silver stain. X 1,000. 

 Fig. 9. (a) Flagella stained by Dr. V. A. Moore's modification of Loeffler"s stain. 

 Bacteria grown for three days in 1.000 cc. of distilled water with addition 

 of 20 cc. of beef broth (see 18th series of inoculations). X 1,000. (b) 

 Flagella ^stained by Dr. Alfred Fischer's stain. Bacteria from an agar 

 culture five days old. X 1,000. 

 Fig. 10. Flagella of Ps.ca»ipe.s-f/-/.s. introduced for comparison. Bacteria from an 



agar culture seven days old. Fischer's flagella stain. X 1.000. 

 Fig. 11. Flagella of Ps. pltaseuli, introduced tor comparison. Bacteria from a 

 culture twenty days old, on nutrient starch jelly with the addition of lactose. 

 Van Ermengem's nitrate of silver stain. Ten minutes in the osmic acid 

 mordant at 55 to 60 C. X 1.000. 

 Fig. 12. Colonies of Ps. hyacinthi from a poured plate (Petri dish) of + 15.5 agar, 

 after sixteen days at 22" to 23 C. The smaller colonies are buried ones. 

 This plate was made from the 1.000 cc. flask culture (18th series of 

 inoculations). The buried colonies are too deep a yellow in the lithograph. 

 Fig. 1 3. A stab culture in 8 per cent nutrient gelatin ( + 48 with malic acid) show- 

 ing the very slow liquefaction. Photographed six weeks after inoculation. 

 Range of temperature. 17 to 20' C. Upper one-half of the gelatin liquified to 

 the walls, bright yellow precipitate and copious yellow rim. Lower one-half 

 clear, solid, unstained, and showing in the center the whitish slender thread 

 of the bacteria growing, very slowly, along the track of the needle nearly 

 to the bottom of the tube. 

 Fig. 14. A stab culture in the same gelatin as 13, but with the addition of 5 per 

 cent cane sugar. Photographed six weeks after inoculation. Range of 

 temperature. 18 to 20 C. Anequally good growth, but liquefaction entirely 

 prevented by the addition of the cane sugar. Compare with alkaline sugar 

 gelatin (text fig. 6. ) 

 Fig. 15. A streak culture on nutrient starch jelly, fourteen days after inoculation. 

 No visible growth, owing to absence of readily assimilable carbohydrate 

 food. Painted by John L. Ridgway. 

 Fig. 16. A streak culture on nutrient starch jelly, fourteen days after inoculation. 

 This culture was an exact duplicate of that shown in fig. 15. except that 

 before the inoculation 20 milligrams of reprecipitated (sugar free) Taka- 

 diastase was allowed to act on the starch one and one-half hours at 34° C, 

 so that some of the starch was converted into readily assimilable substances. 

 The diastase was then destroj'ed by steaming and the slant surface was 

 inociilated in the same way as 15. Painted by John L. Ridgway. 



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