CHAPTER XV. 



THE SEED AND ITS GERMINATION. 



1186. THUS far this treatise has dealt chiefty with the phenom- 

 ena presented by the organs of adult plants, especially while 

 these are in a healthy state. It is necessary to consider in con- 

 clusion a special case ; Darnel}*, that of the seed, and the earliest 

 phases of its independent existence. 



1187. When a fertilized ovule approaches maturity, its activi- 

 ties become notably lessened in degree until, with perfect ripe- 

 ness of the seed, the embryo manifests no indication of life. In 

 a few cases the seed is so precocious that it will germinate even 

 before it is detached from the parent plant ; but there is usually 

 a period of suspended activit}-. 



1188. Two views are held as to the nature of the life of the 

 embryo during this period of arrested activity: (1) that it is 

 simply potential, and may be roughh' compared to the fire in a 

 match, ready to manifest itself under favorable conditions ; (2) 

 that it is a sluggish, dormant state, which differs from active life 

 only in degree. 



1189. From the first point of view it is eas}' to regard the 

 seed as representing a certain amount of potential energy indi- 

 rectly derived from solar radiance, and held for a time in a con- 

 dition from which it may be released in many wa}*s : thus, it may 

 be liberated by rapid combustion, as when corn is burned for 

 fuel ; by slow oxidation, as when seeds decay ; or by the act of 

 germination. 



1190. The second view takes into account, although it does 

 not explain, the slight changes which take place in certain seeds 

 and some other parts, especially buds, during what has been 

 called the resting state. 



1191. It has been stated (976) that many seeds cannot be 

 made to start into active growth, even under the most favorable 

 external conditions, until after the lapse of a definite period. 

 Nothing is }'et known as to the exact structural and other changes 

 which go on by virtue of this peculiarity. 



