A. M. Taylor 261 



comparatively normal conditions, and that a slightly higher percentage 

 had occurred in those kept under the abnormally moist conditions. 



It was here that the effect of the conditions due to advancing 

 spring became evident, for under the influence of the artificial warmth 

 and moisture of the greenhouse a certain proportion of the buds 

 developed prematurely. Such development was however of interest 

 in that a contrast between dormant and expanding buds and the rela- 

 tion of the worm to such expansion was evident. Thus it was found 

 that with a few doubtful exceptions the worms had been able under 

 these conditions to enter the developing buds, while those which 

 remained dormant shewed the presence of worm in the scale leaves 

 only. 



The number of worms found in the infected buds was in all cases 

 small, cast skins were however present in many from which living 

 worms were absent. There was some evidence of decay in the leaf 

 tissue on which living worms were found, but in no case was this 

 sufficient to prevent the normal development of the bud. Such decay 

 was absent from the controls kept under the normal conditions of 

 moisture. 



It is difficult to draw satisfactory conclusions from such results. 

 They appear in the first place to suggest, seeing that the dormant 

 buds remained unaffected except for the presence of the worm in the 

 scale leaves, that the tightness of the true leaves of the buds prevented 

 them from entering these parts and that when this condition was 

 relieved by the expansion of the buds they were able to live there to 

 some extent parasitically. On the other hand, repeated investigation 

 of both hosts in orchards infected with the worm failed to shew their 

 presence even in the scale leaves, nor were the typical symptoms of 

 bud rot and irregular growth present among them. 



The limited number of living worms found within the buds and the 

 presence of cast skins only in so large a proportion of them suggest 

 that the worms finding themselves on an uncongenial host had left 

 such buds to seek new fields for attack. This suggestion is strengthened 

 by the fact that although decay was present it was not comparable 

 with the typical bud rot of black currants produced under similar 

 experimental conditions. 



It is therefore probable, notwithstanding the fact that experi- 

 mentally the worms appeared to be living to some extent parasitically 

 on the red currant and gooseberry, that these species of Ribes do not 

 play an important part as hosts for the black currant worm. 



