22 Proceedings of the Royal Irish Academj/. 



of the remaining five plants there was more than one stalk to each plant; but 

 in each case only one stalk was stabbed and inoculated, the others serving as 

 additional controls, being, however, not stabbed. The inoculations were made 

 just below soU-level, and after they had been made the pots were iilled to the 

 biim with additional soil ; so that the wounds were well below the soil, and 

 hence were kept moist, the controls receiving exactly the same treatment in 

 this respect. The inocidated stalks were marked by tying pieces of coloured 

 wool around them. The experiment was started on July 30th. 



Not until a period of twenty-foui" days had elapsed were any signs of 

 attack noticeable in the fohage of the inocidated stalks. At tins time two of 

 them began to show signs of wilting, which was very marked in one case. 

 After a further period of six days these signs were considerably more pro- 

 nounced, and in another two days a thir-d stalk out of the five inoculated also 

 displayed similar signs. The signs were in all respects similar to those which 

 had been observed on plants growing in the open attacked with the disease. 

 The photogi-aph reproduced on Plate III, fig. 6, shows clearly the appear- 

 ance presented by one of the plants at this date, the contrast between the 

 healthy and the inoculated stalks being plainly evident. 



At tliis time one of the control plants, being less well staked than its 

 fellows, was broken down durrug a storm of wind, but revealed no signs of 

 Black Stalk-rot. The other control plant, as well as the non-stabbed stalks 

 of the inoculated plants, remained perfectly healthy up to the end of the 

 expeiimeut. On the other hand, up to September 21st all five inoculated 

 stalks had shown unmistakable signs of the disease. Doubtless had the 

 experiment been started earlier in the year, and therefore had longer time for 

 development been available, some or perhaps aU of the non-stabbed and non- 

 inocidated stalks belonging to the same plants as the inoculated stalks would 

 have become diseased. 



The stalks which had become aifected were examined, one on Sept. 6th, 

 two on Sept. 19th, and the remaining two on Sept. 21st. It is scarcely 

 necessary to describe in detail the exact appearance presented by the decayed 

 portion of each stalk ; suffice it to say that a rot characteiistic of the disease 

 was foimd in all cases proceeding from the inoculation wound, it beiag ia some 

 cases somewhat more strongly developed than in others. "What is important 

 IS that in four cases out of the five the original pathogenic organism was 

 recovered in pure culture on plating out from the decaying tissues. In the 

 fifth case the organism was also proved to be present with certaiuty, but it was 

 not obtained ui piu-e culture. 



These experiments prove in the clearest possible fashion that the organism, 

 the charactei'S of which are about to be described, is the cause of the disease. 



