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. 



