7. XI. 1903. E. Renter, Hexenbesen und Eriophyiden. 35 



hing der genannten Zweigdeformationen von deren erstem Be- 

 ginn ab verfolgte. Ich erlaube mir ihre Darstellung hier z. T. 

 wörtlich anzuführen: »The formation of the Witch-knots begins 

 with a diseased growth of the mite-infested bud, which is 

 distinguishable by its swelied, irregulär, loosely-opened appear- 

 ance, from the smooth and pointed shape of the buds in healthy 

 condition; and presently . . . the attacked shoot is thickly covered 

 by the buds, which in healthy growth would have been distri- 

 buted at distances of some inches along it. As time goes on, 

 repeated forkings of the twigs from these unhealthy and infested 

 buds, and from successive growths of the same kind, give rise 

 to the knotted and confused masses known as Witches' Brooms. 

 Sometimes these make little progress, and the knöt merely 

 resembles a rough mäss like an old Book's nest thrown down 

 and hanging loosely from the Birch bough; sometimes the twigs 

 regain healthy growth, and pushing on for as much as a yard 

 in length form a pendant mäss of some beauty, from the deli- 

 cacy and gracefulness of the sprays. 



The infested buds . . . may be distinguished by their sphe- 

 roidal shape, greater size, and loosely imbricated irregulär scales, 

 from the natural growths, which are smooth and lanceolate in 

 general outline. A few months låter (about the beginning of 

 February), a touch to one of these distorted buds will often 

 throw off all the diseased scales, and at their bases the coming 

 growth will be found in the numerous minute round buds set 

 close together on the common thickened centre . . . The growth 

 of Ihe knöt from these embryo buds is the work of years; but 

 whilst the tree is still bare of leaves it may be found in every 

 stage of progress: the shortened shoot beset with swollen 

 buds...; the Compound form, where many buds have grown 

 close together so as to present a härd duster, with a few shoots 

 starting from it . . . and so onwards, till the Witch-knot is fully 

 formed, a mäss sometimes more than a yard in diameter^.^ — 

 Diese Bemerkungen werden von instruktiven Figuren erläutert. 



> Ormerod, Manual etc., See. IM., S. 213—214. 



