106 Agrioulthral Experiment Station, Ithaca, N. Y. 



presence within or upon the affected organs, excited them to this 

 abnormal development. 



Two lines of investigation were carried out, having in view the dis- 

 covery of the causal germ. One of these proceeded upon the more 

 customary, but less scientific, lines of inquiry usually adopted in the 

 study of the bacteria of plant diseases, viz. : The inoculation with dis- 

 eased material; the other proceeded upon the more rational line of 

 inquiry chiefly adopted in the study of the bacteria of animal diseases, 

 viz. : The separation of the germs present and inoculations with pure 

 cultures to determine the specific germ. 



Inoculation of healthy plants with diseased material. Experiment 

 No. 1, December 3, 1892. Macerated tissue from freshly developed 

 cushions was gently rubbed between the thumb and finger upon the 

 leaves and stem of a healthy plant. Portions of the affected plant 

 were also left pendent upon the healthy one. JSTo result. 



JEJxperiment N'o. 2, December 3, 1892. Macerated tissue from a 

 plant in the later stages of disorganization was gently rubbed between 

 the thumb and finger upon the leaves and stem of a healthy plant. A 

 portion also of the diseased plant was left pendent upon the healthy 

 one. iVb result. 



Experiment N'o. 3, December 3, 1892, Twenty very young plants 

 freshly potted, just developing the plumule, were treated as follows: 

 There were four uows, five plants in each row. To one plant in each 

 row was applied some of the macerated tissue from freshly developed 

 cushions. Likewise to one plant in each row was applied some of the 

 macerated tissue from a plant in the later stage of the disease. No 

 result. 



Experiment No. 4, December 3, 1892. In a potted plant were made 

 several slit wounds with a scalpel, parallel with the axis of the stem 

 and petiole. Into these were introduced thin longitudinal slices of 

 tissue from freshly developed cushions. The wounds were then wrap- 

 ped with fresh tomato leaves and tied loosely to prevent too great 

 evaporation from the wound. 1 he plant was thoroughly sprayed with 

 water also. No result. 



Experime?it No. 6, December 3, 1892. In like manner a potted plant 

 was inoculated with longitudinal slices from a stem in the later stages 

 of the disease. No restdt. 



Separation of bacteria from affected plants. By the use of sterilized 

 instruments and with precautions against contamination from the 

 outside, portions of the interior of freshly developed cushions were 

 transferred to nutrient agar which contained an infusion of tomato 

 plant. No growth appeared. 



