ADAPTATIONS OF SEEDS AND FRUITS. 225 



seeds which are small, pointed, and covered with hairs. The poste- 

 rior end is prolonged into a hairy, corkscrew-like awn, which twists 

 or untwists, according to the amount of moisture. This awn ends 

 in a feather-like affair with backward-pointed hairs. On moist 

 ground the seed-hairs stand out so as to place the seed-point down- 

 ward, and the awn untwists ; but the barbed feather preventing 

 upward movement, because it catches in the herbage, the seed is 

 forced into the soil. However, if the awn dries and contracts, the 

 feather is easily drawn down while the seed is not drawn up. By 

 successive moistenings and dryings the seed is ultimately driven 

 completely into the earth. 



As to vitality, seeds present widest differences. Very short- 

 lived seeds are those of the coffee and magnolia. On the other 

 hand, under abnormal conditions, some seeds have retained vital- 

 ity for many centuries, apparently. Raspberry seeds, found in a 

 Celtic tumulus along with coins of the Emperor Hadrian, germi- 

 nated, according to good authority, after a possible interval of 

 several centuries. Other seeds from old Roman tombs grew after 

 a lapse of many hundred years, but these are exceptional in- 

 stances. Accurate experiments show that a few kinds live for 

 fifteen years, or thereabouts, while the majority are much shorter 

 lived. Stories of wheat raised from seed found in mummy wrap- 

 pings are founded upon no trustworthy evidence whatever. 



When a forest has been removed by fire, or otherwise, it com- 

 monly happens that a fresh growth of entirely new plants im- 

 mediately springs up. This may be partly due to the unusual 

 opportunity for growth thus given to foreign seeds ; but the usu- 

 ally accepted explanation is that the new growth is from seeds 

 which have long lain dormant. 



Finally, as regards germination, seeds accommodate themselves 

 to surrounding conditions with considerable readiness. Some 

 seeds are so tenacious of life as to germinate, not only when old, 

 but also when a large share of their food substance has been 

 destroyed, provided, of course, that the germ itself is uninjured. 

 No seed, however, will germinate without the proper amount of 

 moisture, free oxygen, and warmth, although other disadvantages 

 are often withstood successfully. 



We have now described some of the more evident adaptations 

 to surroundings displayed in seeds and fruits, but by no means 

 all ; for here, as everywhere else, Nature presents a variety which 

 is almost infinite. Although endless differences in structure are 

 still unexplained, we must believe that they are adaptations to 

 circumstances present or past, and our knowledge leads us con- 

 fidently to expect that future discovery will reveal in increased 

 vastness the complexity of the relations by which everything in 

 Nature is adapted, more or less perfectly, to everything else. 



VOL. XLIII. 16 



