148 THE BEAUTIES OF NATURE CHAP, 
Pinsapo even eighteen. As a general rule 
the Conifers with short leaves keep them on 
for several years, those with long ones for 
fewer, the length of the leaf being somewhat, 
in the inverse ratio to the length of its life ; 
but this is not an invariable criterion, as other 
circumstances also have to be taken into con- 
sideration. 
Leaves with strong scent, aromatic taste, or 
acrid juice, are characteristic of dry regions, 
where they run especial danger of being eaten, 
and where they are thus more or less effec- 
tively protected. 
ON HAIRS 
The hairs of plants are useful in various 
ways. In some cases (1) they keep off super- 
fluous moisture; in others (2) they prevent 
too rapid evaporation ; in some (3) they serve 
as a protection against too glaring light; in 
some (4) they protect the plant from brows- 
ing quadrupeds; in others (5) from being 
eaten by insects; or, (6) serve as a quickset 
hedge to prevent access to the flowers. 
x. eee 
