| Abstract: | At the fifth internode, where a cambial ring was just formed,pressure was applied to the twig surface by girdling it witha rubber tube. This blocked also aeration of the surface. Inthe presence of the compact pith within, the pressure producedthicker wood with a low frequency of pores, in comparison tonormal wood at that region. When the pith was replaced by vaselinethe pressure, without a resistance from the centre, produceda very thin wood with long vessel elements and more abundantrays. Blocking of aeration from outside, without pressure, producedmore abundant vessels. Aeration from the pith region produceda narrower wood zone. Absence of pith (replaced by vaseline)resulted in a wider zone of wood with narrower and shorter vesselmembers. |
