HAY-TIME 157 



thin shell, the cancellous tissue is scanty and large- 

 meshed, and the cavities are filled with air instead of 

 marrow. 



The limbs of many Crustacea and Insects illustrate 

 in their way the advantages of the tubular principle. 

 But the best example of the strength and lightness 

 yielded by the tubular structures of animals is 

 furnished by the hollow quill of a Bird's feather. 



The leaves of grasses are full of curious contrivances, 

 some of which are described and figured by Kerner in 

 his Pflanzenleben (Natural History of Plants}. 



The flowers are expressly adapted to wind-fertili- 

 sation. Notice the absence of striking colour, scent 

 or honey, the abundance of the pollen, the lightly 

 poised anthers, and the feathery stigmas. 



When the fruits ripen and fall off, there fall off with 

 them certain of the enclosing husks. It is only in 

 some cultivated cereals that the artificially enlarged 

 grain can be readily detached from its envelopes. It 

 is not uncommon to find the flower-stalks jointed, so 

 that they readily break away from the haulm. The 

 husks serve to protect the grain from spoiling by rain 

 or drought, and in some cases aid in dispersal by 

 greatly increasing the surface exposed to wind. My 

 old enemy, the Yorkshire Fog, enjoys great facilities 

 for dispersal by wind, and I find it springing up 

 in the most unlikely corners of the garden. In the 

 Reeds of the fenlands some of the inner husks are 

 fringed with long, silky hairs, which act like the hairs 

 on the seeds of Willow, wafting the grain to long 

 distances. Some grasses have awns attached to the 

 husk, which catch in the fleece or fur of animals. In 



