ILLUSTRATIONS. 



Page. 



FIG. 10. Datura metelloides Inoculated by Needle- 

 pricks with Bacterium solanacearum. 

 The same plant as in Plate 4, but six 

 days later 17 



11. (a) Capsule of Organism plated from 



Black Spot of Plum; (b) Viscid Cul- 

 ture-medium from which a was ob- 

 tained 18 



12. Yellow Ooze from Black Spot of Plum 



stained by ordinary method 19 



13. Tenuous Threads of Bacillus tracheiphi- 



lus drawn from a Muskmelon Stem . . 19 



14. A detail from Fig. 13, highly magnified. 19 



15. Flagella stained from a pure culture of 



a Bacterium grown in Water contain- 

 ing a few drops of Uschinsky Solution. 21 



16. Beyerinck's Drop Bottle 21 



17. Double Blow Bulb 22 



18. Short Form of Bacterium campestre 



when crowded 23 



19. Long Form of Bacterium campestre 



when grown on Sugar-agar 23 



20. Hanging-drop Culture 24 



21. Involution-forms of Bacillus tracheiphi- 



lus 24 



22. Y-shaped Forms from Root-tubercles of 



Clover 24 



23. Zeiss Compensating Ocular, with Screw 



or Filar Eye-piece Micrometer 25 



24. Zeiss Upright Photomicrographic Cam- 



era 26 



25. Hand-lens for examining Bacterial Cul- 



tures 27 



26. Hand-lens for examining Bacterial Cul- 



tures, showing another form of mount. 27 



27. Zeiss Cover-glass Measurer 28 



28. Nelson's Photographic Gelatin 30 



29. Agar-agar as received from Japan. 



(Slender "Kanten") 31 



30. Another form of Agar-agar made in 



Japan (Square "Kanten") 32 



31,32. Gelidiums furnishing Agar-agar... 33,34 



33. Agar-agar Flour as received from Euro- 



pean Manufacturers 35 



34. Schleicher and Schull's Folded Filter 



Papers 36 



35. Thermo-regulator for Blood-serum Oven. 37 



36. Iris-rhizome-rot Organism grown on 



Sterile Raw Carrot 41 



37. Tin-box in which Pipettes, Scalpels, etc., 



may be sterilized 42 



38. Fluid Culture showing rise of Viscid 



Precipitate when twirled rapidly 42 



Page. 

 FIG. 39. Platinum-iridium Transfer Wires 43 



40. Simple way of filtering with Chamber- 



land Bougie 44 



41. Roux Filter for separating Bacteria 



from their Products 45 



42. Section of the Arnold Steam Sterilizer, 



showing Principle of Action 46 



43. Lautenschlager Centrifuge 47 



44. Wire-crate for holding Media to be ster- 



ilized 48 



45. Oven for use in solidifying Blood-serum, 



etc., at Temperatures below 100 C. .. 49 



46. Simple Rack for holding Fermentation 



tubes 52 



47,48,49. Fermentation-tubes in actual use. . 53 



50. Ordinary Kipp Gas-generator 54 



51. Hempel's Burettes for Gas-analysis 55 



52. Hempel's Simple Pipette for Liquid Re- 



agents 56 



53. Small Novy Jar 57 



54. Large Novy Jar; the most convenient 



Form 58 



55. Simple Device for growing organisms in 



Nitrogen ....'. 59 



56. Test for Reduction of Nitrates to Ni- 



trites 63 



57. Crystals formed in Nutrient Agar as the 



Result of Bacterial Growth 66 



58. Thick-walled Flask for Filtration or 



Evaporation in vacua 67 



59. Titration-devices 68 



60. Sodium-hydrate Bottle 69 



61. Effect of Sunlight on Pear-blight Ba- 



cillus 71 



62. Effect of Sunlight on Bean-spot Bacte- 



rium 71 



63. Water-bath for Thermal Death-point 



Experiments 76 



64. Roux Metal-bar Thermo-regulator 77 



65. Thermometer for Thermal Death-point 



Experiments 79 



66. Leveling Apparatus 80 



67. Dewar Glass for Experiments with 



Liquid Air 81 



68. Petri-dish Poured Plate inoculated with 



a measured quantity of a Bouillon 

 Culture of Bacillus tracheiphilus 82 



69. The same as Fig. 68, but poured after 



Exposure to Liquid Air 83 



70. 'Stomatal Infection by Bacterium pruni 



in Green Fruits 84 



71. Stomatal Infection by Bacterium pruni 



in Leaf 86 



72. Stomatal Infection by Bacterium pruni 



a. Later Stage in Fruit 88 



