97 



Fig. 3. Iiifcclion of Pseudomonas citri llirough 

 a stoma or breathing pore with bacteria 

 in siibslomatal cavity, and adjacent inter- 

 cellular spaces, seventy two hours after 

 inoculation. 



When once the bacteria are within the host tliey 

 multiply rapidly, effect a passage between the host cells 

 and come to occupy the intercellular spaces. Their 

 presence within the tissues is evidenced in three to five 

 days by oily or watery dots which within another week 

 will have developed into open cankers. At this stage 

 before the exposed cankerous cells have become dry, 

 the greatest danger of spreading the disease exists. 



Effect Upon The Host. 

 The most manifest effect of canker upon the host, 

 as determined by microscopical examination, is the en- 



Fig. 4. (a) l\seud()ni<)nas cilii occurring be- 

 tween the cells of the niesophyll tissue 

 and (b) of the palisade parenchyma. 



largement of affected cells Little if any cell division in 

 cankerous tissue is believed to occur. The tension re- 



