61, 62.] THE SEED. 73 



two modes are to be specially noticed. 1. Incumbent, 

 when the cotyledons fold over so as to bring the back 

 of one against the radicle (Shepherd's Purse) ; 2. Ac- 

 cumbent, when the edges touch the radicle (Arabis) . 



184. A few plants, as the Onion, Orange, and Coniferse, occasionally have 

 two or even several embryos in a seed ; while all the Cryptogamia or flower- 

 less plants have no embryo at all, nor even seeds, but are reproduced from 

 spores bodies analogous to the pollen-grains of flowering plants (217). 



185. Vitality of the seed. After the embryo has 

 reached its growth in the ripened seed, it becomes 

 suddenly inactive, yet still alive. In this condition it 

 is, in fact, a living plant, safely packed and sealed up 

 for transportation. This suspended vitality of the seed 

 may endure for years, or even, in some species, for 

 ages. The seeds of Maize and Rye have been known 

 to grow when 40 years old; Kidney-beans when 100; 

 the Raspberry after 1700 years (Lindley). Seeds of 

 Mountain Potentilla were known to us to germinate 

 after a slumber of 60 years. On the other hand, the 

 seeds of some species are short-lived, retaining vitality 

 hardly a year (Coffee, Magnolia). 



186. The dispersion of seeds over wide, and often to distant regions, is 

 effected by special agencies, in which the highest Intelligence and Wisdom 

 are clearly seen. Some seeds made buoyant by means of the coma or pappus, 

 already mentioned, are wafted afar by the winds, beyond rivers, lakes, and 

 seas ; as the Thistle and Dandelion. Other seeds have wings for the same 

 purpose. Others are provided with hooks or barbs, by which they lay hold of 

 men and animals, and are thus, by unwilling agents, scattered far and wide 

 (Burr-seed, Tick-seed). Again : some seeds, destitute of aU such appendages, 

 are thrown to a distance by the sudden coiling of the elastic carpels (Touch- 

 me-not). The Squirting-cucumber becomes distended with water by absorp- 

 tion, and at length, when ripe, bursts an aperture at the base by separating 

 from the stem, and projects the mingled seeds and water with amazing force. 



187. Rivers, streams, and ocean currents, are agents for transporting 

 seeds from country to country. Thus the Cocoa, and the Cashew-nut, and 

 the seeds of Mahogany, have been known to perform long voyages without 

 injury to their vitality. Squirrels laying up their winter stores in the earth ; 

 birds migrating from clime to clime and from island to island, in like manner 

 conspire to effect the same important end. 



