Chances of Life 289 



and then, at long intervals, once in a few centuries, the 

 stock will be kept up, though not increased. 



Small seeds have a better chance in some ways, as 

 they are more easily sheltered, and hidden from the 

 bright keen eyes of the birds. A bed of damp moss is 

 a capital hiding-place ; and so are the cracks which 

 open in the soil when the earth is dry ; for these close 

 up again when the wet comes, and the seeds are safely 

 buried out of harm's way. Cracks may often be seen 

 full of seeds. 



Still, * if you want a thing done, do it yourself,' is an 

 excellent motto even for seeds, and it is an advantage 

 to be independent even of cracks ! This is what some 

 seeds are, especially a good many grass-seeds ; for 

 instead of waiting to be buried, they set to work and 

 bury themselves. 



The seed of the grass Aristida, for instance, is 

 enclosed in a couple of husks tipped with bristles, each 

 divided into three fine tails, six or eight inches long, 

 which stand out in different directions more or less at 

 right angles to the seed. When the seed falls to the 

 ground the tails keep it upright, and as they dry and 

 twist, they make it turn round and round on its point, 

 which is barbed with flint ; and so it bores its way 

 into the earth, the barb holding it fast, so that it cannot 

 be blown away by wind. 



Another self-burying seed is that of one of the 

 Cranesbills, which is nearly related to the geranium. 

 The fruit of this httle plant consists of four or five 

 miniature arrows, which are the hardened and much 

 lengthened carpels, each having its ovary (containing a 

 single seed) at the lower end. At first they are fitted 

 closely together round a central spike, and form the 



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