THE SEED. 61 



glance by the structure of their leaves, which are ntt-veiiied 

 ( 280). More than two cotyledons are found in the seeds of 

 Pine and Fir ; while the Dodder is almost the only known exam- 

 ple of an embryo with no cotyledon. 



183. The position of the embryo, whether with or without 

 albumen, is singularly varied and interesting to study. It may 

 be straight, as in Cat-tail and Violet, or curved in various de- 

 grees (Moonseed and Pink), or coiled (Hop), or rolled (Spice- 

 bush), or bent angularly (Buckwheat), or folded (Cruciferse). 

 In the last case two modes are to be specially noticed. 1, In- 

 cumbent, when the cotyledons fold over so as to bring the back 

 of one against the radicle (Shepherd's Purse) ; 2, accumbent, 

 when the edges touch the radicle (Arabis). 



184. A few plants, as the Onion, Orange, and Coniferae, occasionally have two or even 

 several embryos in a seed ; while all the Cryptogamia or flowerless plants have DO em- 

 bryo at all, nor even seeds, but are reproduced from spores bodies analogous to the pol- 

 len-grains of flowering plants (217). 



185. Vitality of the seed. After the embryo has reached 

 its wonted growth in the ripened seed, it becomes suddenly inac- 

 tive and torpid, 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 30 to 40 years old ; Kidney- 

 beans when 100; the Raspberry after 1700 years (Lindley). 

 Seeds of Mountain Potentilla (P. tridentata) were known to us 

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

 the seeds of some species are bhort-lived, retaining vitality hardly 

 a year (Coffee, Magnolia). 



186. Tlie 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 i 

 have wings for the same purpose. Others are provided with hooks or barbs, by which 

 they lay hold of men and animal;?, and are thus, by unwilling agents, scattered far and 

 wide (Burr-seed, Tick-seed). Again: some seeds, destitute of all 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 absorption, 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 coun- 

 try to country. Thus the Oucoa, and the Caehew-nut, and the seeds of Mahogany, have 



