166 JOUE^'AL OF THE EOYAL HORTICULTUEAL SOCIETY. 



found that no mites had penetrated into its interior, although after a 

 period of twenty-four hours had elapsed numerous mites were discovered 

 under the bud- scales of the terminal healthy bud. During the migration 

 from diseased to healthy buds numerous mites were observed undergoing 

 the peculiar swaying process described above, which suggests that fecunda- 

 tion is effected during the journey between old and new buds. 



After the shoot had been under observation for three days a whitish 

 streak, about a quarter of an inch long, appeared a short distance below 

 the terminal bud. On examination under the microscope this streak was 

 seen to consist of a dense assemblage of mites that had stuck fast in some 

 sticky. substance that had accidentally touched the shoot. 



This discovery furnished the clue for all further experiments. 



Fig. 38. — Black Cubraxt Gall Mite. Fig. 39. — Hazel Gall Mite, Eeiophes 

 Eriophes ribis. Highly Magnified. A^■ELLA^'EA. Highly Magnified. 



Other healthy shoots to which " big- buds " were fixed with " seccotine " 

 were procured. On one such a ring of vaseline, a quarter of an inch broad, 

 was painted round the shoot between each "big-bud" and the healthy 

 bud immediately above it. Myriads of mites were entrapped in the vaseline, 

 but not a single mite succeeded in crossing the danger zone and reaching 

 the healthy bud situated above. In another experiment the "big-buds" 

 were thinly covered with vasehne ; in this instance not a single mite 

 escaped from the infected buds, as proved by their absence on the vaseline 

 rings present on the shoot above the infected buds. Finally, rings of 

 vaseline painted round a shoot both above and below each infested bud 

 showed that the mites almost invariably ascended the stem, in the 

 direction of the new and healthy buds. 



It was observed that as soon as the mites left an old diseased bud they 

 were very anxious to gain an entrance into another healthy bud, which 



