242 ON THE SEED. 



Mrs. B. The radicle first sprouts from the aperture 

 with the neck situated at its base ; from this vital spot 

 the plumula shoots upwards ; but the young plant re- 

 mains attached to the pericarp by the neck, until it has 

 consumed the albumen of the seed, and is able to supply 

 itself with food from the soil. 



It is thus that monocotyledons are ushered into life. 

 The germination of dicotyledons is somewhat different. 

 The seed is not enveloped in its pericarp, and, when it 

 begins to germinate, the spermoderme cracks and falls 

 off; the cotyledons, commonly called the lobes of the seed, 

 are split asunder by the stem which rises between them ; 

 but, like a careful parent, they follow their nursling at 

 its entrance into life, and continue to supply it with food 

 until its roots are sufficiently strong to perform that office. 

 The embryo plant consists, then, of three parts : the 

 radicle, or root ; the plumula, or little stem ; and the cot- 

 yledons, or seminal leaves, which make their appearance 

 at the base of this stem. 



The first and most essential circumstance requisite for 

 germination is moisture ; for a seed, in germinating, ab- 

 sorbs about once and a half its weight of water. 



Emily. This is, no doubt, for the purpose of softening 

 and dissolving the hardened contents of the cotyledons, 

 and rendering them sufficiently limpid to pass through the 

 minute vessels which convey them into the embryo plant. 



Mrs. B. Yes ; moisture is equally necessary, wheth- 

 er the germinating plant be fed by the farinaceous matter 

 of the cotyledons or by albumen ; for seeds, when ripe, 

 you know, are perfectly dry, or if they contain any water, 

 it is not in a state of liquidity, but solid, like the water of 

 crystallisation in mineral salts. If seeds are deficient in 

 moisture, they are, on the other hand, overladen with 

 carbon, so that you must supply them with water, and 

 free them from a portion of their carbon, to enable them 

 to germinate. It is the great quantity of carbon which 

 seeds require in ripening that exhausts the soil in which 

 they grow. 



1320. How is the first germination described 1 1321. How does 

 the germination in monocotyledons and dicotyledons vary 1 ? 1322. Of 

 how many parts does the embryo plant consist and what are theyl 1323. 

 What is the first and most essential circumstance requisite for germina- 

 tion'? 1324. For what purpose is the moisture needed 1 ? 

 What effect on the carbon is caused by a deficiency of moisture 1 ? 

 What exhausts the soill 





