262 Scientific Proceedings, Royal Dublin Society. 



for the most part, formed on eonidiophores which sprang from these hyphae 

 and had burst through the outer wall of the epidermal cells. The eonidiophores 

 resembled those of P. lini as found on browned flax, but they were not 

 grouped together as they occur when protruding through a stoma. They 

 were more or less isolated, and emerged singly and in an irregular manner 

 all over the surface of the seed, so that definite acervuli were not produced. 

 At the hilum the conidiophoi'es were produced in greater quantity than 

 elsewhere. Two simple eonidiophores producing conidia on the surface of a 

 seed are shown in fig. 7, Plate X. 



As has previously been stated, the fungus hyphae in the seed-coat can 

 clearly be traced in the epidermal and underlying parenchymatous tissues as 

 far as the outer edge of the fibrous cells, but they have never been seen to 

 penetrate the latter. 



Occasionally masses of conidia have been found completely filling 

 individual cells of the dead parenchymatous tissue beneath the epidermis, 

 and in some cases they are formed in the epidermal cells themselves. 

 Generally speaking, however, they are produced on the exterior of the 

 seed-coat. 



Owing to the rupture of the cuticle and walls of the epidermal cells by 

 the eonidiophores of the fungus, affected seeds absorb water more rapidly 

 than healthy ones do ; consequently such seeds become mucilaginous more 

 quickly, and this fact is an aid to their detection. 



Trials were made to ascertain whether the conidia present on the seed-coat 

 were alive, and, if so, whether they had any connexion with the outbreak of 

 " browning " on the plants in the field. They were found to be alive, and by 

 the ordinary poured plate method pure cultures (starting in every case from a 

 single couidium from the surface of an affected seed) were raised. Further, 

 by comparative cultural tests the fungus so obtained was proved to be identical 

 with that isolated by means of the conidia taken from browned stems, leaves, 

 and fruits. 



As a result of microscopical examination, fifty-two seeds bearing conidia 

 were picked out from a sample which had produced a browned crop the 

 previous year. These seeds were sown approximately one inch deep in a pot 

 of sterilized soil, and after sowing the pot was covered with a bell-jar and 

 kept in an unheated greenhouse. Since the seeds were sown in October, 

 germination was slow, and the plants, which were examined daily, made 

 poor growth. 



The first sign of disease was noticed on the thirtieth day after sowing. 

 The cotyledons of several of the seedlings showed little brown rounded areas, 

 which gradually increased in size and became dark in colour. The experiment 



