228 ABSORPTION OF RAIN AND DEW BY THE FOLIAGE-LEAVES. 
by rain and retain a considerable quantity of water. The water that they cannot 
hold they conduct downwards to the ciliate axils of the next lower pair of leaves, 
where it is drawn through the lash-like hairs in due course and collected into a 
ring of water surrounding the node (see fig. 52°). If this accumulation of water 
becomes so voluminous and heavy that it cannot any longer be retained by the 
fringe of lashes, the surplus glides on to the unilateral ridge of hairs on the adjacent 
internode down to the pair of leaves below. Accordingly, after a shower every 
node from which leaves arise is seen to be inclosed in a water-bath, and the hairy 
IT 
SA 
x 
Fig. 52.—Hairs and Leaves which retain Dew and Rain. 
1 Dwarf Gentian (Gentiana acaulis). 2 Lady’s Mantle (Alchemilla vulgaris). 3 Chickweed (Stellaria media). 
ridges also are so soaked with water that they look like edgings of glass. All the 
individual cells in each of the hairs are full of protoplasm and cell-sap, but only the 
lowest, which are very short, really act as absorption-cells. When these cells 
become at all relaxed in dry air, the fact is indicated by the appearance on the 
external cell-wall of fine stri (see fig. 53! and 532). The protoplasts inhabiting them 
attract water, and after being relaxed in the manner referred to the cells regain 
their turgidity on being wetted, whilst the fine wrinkles on the outer membrane are 
in consequence immediately smoothed out. Although the upper cells of the hair 
possess a less thick cuticle, they, on the other hand, seem not to absorb any water, 
but to serve rather to conduct it by their surfaces. 
This case is, as we have said, comparatively rare, and the corresponding absorp- 
