66i 
the Ascent Water in Trees . 
medium in which it was immersed might be illustrated by the cases of 
a wet and dry fabric ; the first freely permeable to water, the second 
freely permeable to air. Capillary resistance destroys the free 
permeability when it is sought to pass through the fabric a medium 
differing in physical properties from that already contained in the 
openings or meshes of the fabric. The fact that the wet fabric was 
not permeable by air illustrated the properties of the cell-wall in 
retaining a bubble developed within the lumen. 
After some remarks from Professor Marshall Ward, the dis- 
cussion closed. 
