The outgrowth tissues induced by Pseudomonas phaseolicola and P. lachrymans were characterized by the striking hypertrophy and the less extent of hyperplasia. A soft rotting pseudomonad, however, produced the outgrowths mainly consisting of hypertrophied cells. Another histopathological characters of the outgrowth tissues were consumption of starch grains. With the initiation of hypertrophy, starch grains became less in number and smaller in size, and then completely depleted with the cell enlargement or cell divisions progressed. Simaltaneously, ß-amylase activity greatly rose in the tissues which were in the earlier stage of the changes, but α-amylase activity did not show any significant rise. In contrast, the amylase activities were markedly reduced in the hypertrophied area. The weight of slices inoculated with plant pathogenic bacteria showed only slight increase by the outgrowth formation compared to that of uninoculated control. Dry weights in the hypertrophied area, however, decreased to about 60% of those in the uninoculated healthy tissues. The loss of dry weight in hypertrophied area seems to be replaced by uptake of water.