DISCUSSION. 179 



give a single example, Dorsett has obtained excellent results in 

 producing disease resistant violets. Plant breeding is becom- 

 ing a more and more important phase of the subject, and I be- 

 lieve we are just beginning a v^ork that offers much of promise. 

 It remains for farmers, and scientific agriculturists, and prac- 

 tical horticulturists, pathologists and plant breeders to still fur- 

 ther co-operate w^ith each other in the prosecution of the 

 work. 



After all when we consider the varied problem that the plant 

 pathologist has to deal with, and the complicated methods that 

 it has been necessary to discover and perfect for the prosecu- 

 tion of the work infield, green-house and laboratory, it is not 

 strange that it has required the accumulated results of nineteen 

 centuries of human progress to place the scientific study of 

 plant diseases on a firm and enduring foundation. Much has 

 already been accomplished, but we look to the future for 

 still greater achievements. 



DISCUSSION. 



Mr. Masters: Do you consider that it is the same bacteria 

 that produces the blight on plums and pears? 



Prof. Heald: It is the same organism exactly. 



Mr. Masters: What would you expect if you took a knife 

 and cut into a blighted limb on a poor tree, and then cut into a 

 healthy limb of another tree? 



Prof. Heald: I would expect that you would carry over from 

 the blighted limb a disease and establish it in the healthy limb. 



Mr. Masters: If you cut into this same blighted limb, and 

 then cut into a water sprout on an apple tree, would you expect 

 the apple to blight? 



Prof. Heald: Yes sir. 



Mr. Masters: Well, that has not been my experience. I 

 think in about twenty experiments I made on pears, that in 

 every case it did not produce blight. I did'nt get a blight in 

 the whole lot. , 



Prof. Heald: Probably those organisms had become so 



