272 Scientific Proceedings, Royal Duhlin Society. 



This fungus was isolated, studied in pure culture, and was proved by 

 means of controlled inoculation experiments to be the cause of both 

 " browning " and " stem-break." 



Not having previously been recorded, the fungus is described under the 

 name Polyspora lini n. gen. et. sp. 



Diseased plants produce infected seed, and it was proved that transmission 

 of the disease occurs through the sowing of such seed. It is probable that 

 this is the chief, if not the only, means by which the disease is perpetuated. 



The fungus has been found on flax seed definitely known to have been 

 produced in England and Scotland, as well as on seed purporting to have 

 come from a crop grown in Belgium. It has also been found on flax grown 

 in Ireland from seed believed to have been derived from crops grown in 

 England, Scotland, Holland, Russia, Canada, and Japan, and the disease has 

 been reported as being present on flax in British East Africa. It would 

 appear, therefore, that the disease must be present practically wherever flax 

 is cultivated. It is possible, however, that, owing to different climatic 

 conditions, it may not be so serious in certain of these countries as it is in 

 Ireland. 



Seed for sowing purposes should not be saved from a crop suffering from 

 this disease. Seed disinfectioir ti'ials on a small scale have shown that 

 atomising with a dilute aqueous solution of formaldehyde is one of the most 

 promising means of control when healthy seed is not available for sowing. 



Both white-flowered and blue-flowered varieties of flax have been found 

 susceptible to the disease. 



