A. M. Taylor 259 



On the other hand should such worms be in a motile instead of 

 a quiescent condition, so rapid are their movements that they could 

 utilize the short period during which the drop of rain immersed the 

 bud to penetrate the scale leaves. 



There is yet another condition which may have influenced the 

 results obtained in this experiment. The atmospheric condition of 

 the greenhouse in which the plants were kept was unnaturally dry — 

 this had the effect of causing the stems of the seedlings to dry rapidly 

 after they had been watered, thus restricting the period of activity 

 on which the distribution of the worm depends. Under normal con- 

 ditions in the open the stems of the trees remain covered with a film 

 of water for some considerable time after rain has fallen, especially 

 in the case of moss-covered trees. Such a statement applies to normal 

 rainy weather and not to heavy showers followed by brilliant sunshine. 



Section IV. 



To proceed to the latter part of the experiment which deals with 

 the effect of light rain and heavy mists on migrating bodies of worms. 



This experiment resembles the foregoing in that the plants were 

 divided into two series and inoculated, (i) by means of the soil, and (ii) by 

 direct bud inoculation ; but differed in that they were sprayed twice daily 

 with a spray producer. At the termination of the experimental period 

 it was found upon examination that approximately one-half of the 

 buds of the seedlings thus treated had become infected with worm. 

 These results suggest therefore that under conditions of light rain 

 and mists the worms are able to distribute themselves with greater 

 ease than under conditions of heavy rain. This is probably the case 

 under normal conditions in the orchard. Heavy mists are usually 

 of lengthy duration and while they prevail the worms would regain 

 their activity and proceed in the film of moisture, resulting from atmo- 

 spheric condensation, to invade the surrounding buds. 



The experimental work dealing with the migration, and the influence 

 of atmospheric conditions on that period, has now been given. It 

 is however important to realize that such work can at its best but 

 roughly indicate the probable habits of the worms under normal 

 conditions. The results of this experimental work are here given in 

 tabulated form. 



