74 Scientific Proceedings, Royal Dublin Society. 



With regard to the " misses," these were due in the two cases of autumn- 

 cut heels to the sets succumbing apparently to a soft bacterial rot. In the 

 spring-cut heels the miss in one case was evidently due to the attacks of 

 slugs, and in the other a weak shoot had developed from the small set, which, 

 however, had also been attacked and was not strong enough to reach above 

 ground. Verticillium was found to be present in the vascular tissues of the 

 remaining more or less sound portions of these sets in July. The miss in the 

 case of the autumn-cut roses was due to the removal of the set, probably by 

 a rat or a jackdaw, as both of these animals were observed at various times 

 to be active in this manner on neighbouring plots. It is not believed that the 

 presence of Verticillium albo-atrum in the sets was the cause of any of these 

 misses. This point will be referred to again later in this paper. 



It is scarcely necessary to go into the details of the development of the 

 plants from these various sets ; suffice it to say that many of them, from roses 

 as well as heels, were small from the start and soon showed signs of the 

 disease, dying away soon after the middle of July. Others were larger and 

 lasted longer, while comparatively few lasted out the season. In all cases in the 

 table where the plants are described as containing Verticillium, it should be 

 understood that this was determined both by microscopic examination and 

 by cultural methods. The same methods were applied and gave negative 

 results in the cases of the plants described as being without Verticillium. 



It will be seen, as was to be expected, that a very high percentage of the 

 heel-end sets, both autumn-, and spring-cut, gave diseased plants ; nevertheless 

 a few of them gave healthy plants, from which it follows that an affected set 

 or tuber, although it generally gives rise to a diseased plant, does not neces- 

 sarily do so. Further evidence of this will be adduced presently. It may 

 also fairly be concluded that even in the autumn the fungus must have 

 reached in very many cases (sixty-three per cent, in this particular experi- 

 ment) the rose-end half of the tuber, and that consequently it is not correct 

 to regard the fungus as generally hibernating in a more or less strictly 

 localized position at the very heel- end. 



Further, since the percentage of diseased plants arising from the spring- 

 cut rose sets is considerably higher than that of the corresponding 

 autumn-cut ones, it may be concluded that the mycelium does make some 

 progress from the heel towards the rose-end of an affected tuber during 

 storage over winter. 



The fungus has been isolated from the vascular tissues of various regions 

 in tubers both before planting and also at the close of the season when they 

 have produced diseased plants. (See fig. 1, Plate III.) It has never been 

 observed to spread from the wood vessels to the surrounding tissues in the 



