There are no changes in cell dimensions more than 10 cm above a girdle in white pine (Pinus strobus L.), but up to 10 cm above, cell radial diameters are less, and at 2 cm cell walls may be thicker. There is an increase in number of cells produced from 2 to 310 cm above girdles, apparently because of a higher mitotic index and longer season for mitotic activity. The radial number of cells in the cambial zone does not change. From 2 to 310 cm below girdles mitotic activity and radial enlargement soon stop, cell wall thickening continues slowly, and there is no change in radial cell number in the cambial zone. These effects above and below girdles appear to be independent of time of girdling. They may be explained by the effect of girdling in blocking both the polarized auxin transport system and the non-polarized phloem transport system.