256 Black Currant Eelworm 



as in the previous section by placing the diseased buds in close proximity 

 to the stems of the seedlings. The plants and worms were in this 

 manner kept throughout the experiment under the influence of a 

 sufficient amount of moisture to maintain a continuous film of water 

 over the buds and stems. 



At the termination of the six weeks' period it was found that of the 

 150 buds kept under these conditions four only remained unattacked. 

 The attacked buds shewed the typical symptoms of discoloration and 

 decay and the worms in them were plentiful and reproducing freely. 

 Especially were the terminal and apical buds and those beneath the 

 soil surface in an advanced stage of decay and the number of worms 

 contained in them was phenomenal. Examination of the stems and 

 roots shewed that the worms were absent from these parts. The 

 control plants in this section were in all cases found free from worm, 

 but a certain amount of discoloration was present in many buds, which 

 condition was however anticipated and accounted for by the unnatural 

 state of moisture and airlessness in which they had been kept. Many 

 of these buds had, under the influence of warmth and of moisture, 

 pushed into growth and not a few were attacked by Botrytis. 



Surplus control plants which were included in this experiment 

 and not needed for dissection were grown on subsequently under normal 

 conditions. These, with the exception of a few buds which failed to 

 expand, developed normally, thus proving that the abnormal conditions 

 under which the experiment had been conducted had not seriously 

 influenced the results obtained. 



From this section of the experiment it may be concluded that under 

 the influence of moisture the worms can ascend from the soil to the 

 buds above the soil surface and descend to those below it. The results 

 also tend to confirm the supposition that the worms are ectoparasitic 

 in their habits and travel externally by the stem from bud to bud, 

 and not by the internal tissues. 



A further experiment acting more or less as a check on the fore- 

 going section was carried out in the following manner. Pots containing 

 soil only were inoculated as in the previous cases with diseased buds 

 heaped on the soil surface. For a period of six weeks moisture was 

 entirely withheld from these pots^ after which time they were watered 

 freely. Cuttings from disease-free seedlings were then inserted in the 

 infected soil of these pots — half of the pots and cuttings were then 

 transferred to the moist conditions of the previous section and half 

 were kept under the conditions of drought as in Section I. At the 



