260 Scientific Proceedings, Royal Dublin Society. 



After a lapse of sixteen clays the plants in the plot sprayed with the 

 conidial suspension had become distinctly brown, and resembled in every 

 detail those naturally affected witli the disease. Those in the control plot 

 assumed the normal golden colour characteristic of healthy ripe flax, and 

 showed not the slightest trace of " browning." 



The " stem-break " phase of the disease was also artificially reproduced 

 in the following manner : — Two pots of soil were sterilized as before, and 

 flax seeds proved to be fungus-free were sown in each. After sowing, the 

 plots were covered with bell-jars and kept in the greenhouse. When the 

 seedlings were about one and a half inches high all the cotyledons of the 

 plants in one pot were wetted with sterile water, while the cotyledons of those 

 in the second pot were smeared vs'ith conidia from a twelve-day-old pure 

 culture of the fungus. The bell-jars were then replaced. During subsequent 

 waterings of the soil care was taken not to wet the cotyledons ; consequently 

 the conidia remained undisturbed on them. 



The smeared cotyledons showed the first signs of infection seventeen days 

 after the conidia had been applied to them. Tliey gradually turned brown, 

 and, owing to the general infection which took place over their whole 

 surfaces, isolated spots did not develop. The progress of the fungus along 

 the cotyledons was followed until the latter reached the main stems of the 

 plants at the nodes. Here it continued to spread, with the result that the 

 tissues of the stem became diseased and brown ; but its further progress was 

 not rapid, and the injury was more or less localized. 



Twenty-four days after smearing all the cotyledons were dead, brown, 

 and shrivelled, and one plant had toppled over, the stem being nearly broken 

 through a little below the first node. Jn this case the disease extended 

 down along the stem for .approximately half an inch ; but the greatest 

 damage to the tissues occurred where the partial fracture took place. 



The experiment was continued for forty-six days, by which time five 

 other plants had fallen over, the partial fracture of the stem being at the 

 first node in each case; see fig. 1, Plate IX. The remaining plants were 

 then carefully examined, and in every case their stems at the point of 

 insertion of the cotyledons were found to be more or less diseased. Owing to 

 the tranquil conditions prevailing landerneath the bell-jar, they continued to 

 remain erect, but had they been subjected to the disturbing effects of wind 

 and rain, such as would be the case under open field conditions, many more 

 of them would, in all probability, have fallen over. 



The dead cotyledons and the diseased areas on the stems of those plants 

 that had fallen over were examined microscopically, and typical acervuli of 

 the fungus were found in abundance on them. Finally, it was proved by 



