Green Leaves at Work 1 13 



its habitat. The slender blades and delicate 

 fringes are adapted, like fishes' gills, to bring the 

 greatest possible area of surface into contact with 

 the water, and thus, also, with the air, which is 

 diffused through it. 



And the waves and currents, which might tear 

 a broad leaf to ribbons, glide harmlessly through 

 these blades and fringes, just as the ocean gales, 

 which rip the Canna leaves in our summer cottage- 

 gardens into " smithereens," sough harmlessly 

 through the slender needles of the coast pines. 



The thick, fat foliage of the house-leek, the 

 aloe, and the century-plant does double duty. 

 These leaves not only prepare nourishment for the 

 plant, but also serve as storehouses to hold it. 



Their whole interior is white as that of a potato, 

 and, like that useful vegetable, they are heavily 

 loaded with starch, while their green surfaces fulfil 

 the ordinary use of foliage transpiration and di- 

 gestion. 



As an Irishman might put the case, there are 

 leaves which are not leaves at all but are some- 

 thing else. 



At the end of a climbing spray of the pea or 

 vetch the topmost leaf or a part of it becomes 

 (Fig. 23) a tendril by means of which the vine clings 



