100 ROTANY FOR BEGINNERS. j Cll. XVI. 



the moisture proceeds ; while some imagine that the plant is en- 

 dowed with a kind of instinct, similar to that which appears in 

 animals, leading the little duck to seek the water, and birds to 

 attempt to fly but let us call this power by what name we 

 will, or refer it to whatever secondary laws, we must after all 

 attribute it to the will and design of Him, who gave the plant 

 a principle of life. 



415. After the young root has made some progress, the coty 

 ledons swell, and rising out of the ground, form two green leaves, 

 called seed leaves. You have no doubt noticed their appear- 

 ance in the garden bean, when it first appears above the ground 



416. When the plume develops its leaves, these seed-leaves, 

 being no longer needed, wither and decay. 



417. You will recollect that the embryo or germ is composed 

 of two parts, the radicle and the plume. The radicle, we have 

 just seen, extends itself downwards. Soon after this part of 

 the germ has begun its downward course, the plume, (so called 

 from its resembling a little feather,) rises upwards, and soon 

 becomes a tuft of young leaves, with which the stem, if there 

 is one, ascends. 



418. Some moisture is essential to the germination of the 

 seed, though different plants require different quantises. Wa- 

 ter softens the envelopes of the seed, swells the k-rnel, and 

 causes it to burst. Too much w r ater produces a decay or rot in 

 the seed so rapidly, that the living principle is destroyed rather 

 than brought forward ; hence it is better to sow seeds in dry ra- 

 ther than wet weather. Ea?*lh, though not absolutely essential, 

 is useful, as affording to the vegetable egg a favourable situa- 

 tion, where it may receive the influence of the various agents, 

 which are to perform their offices in the development of its 

 parts. Some plants vegetate without earth. The parasite grows 

 upon tne barks of other plants ; many seeds vegetate in water, 

 and some, when moistened and placed on cotton, or any other 

 supporting substance. 



419. Air is essential to vegetation ; under an exhausted recei- 

 ver a seed will not germinate, although possessing every other 

 requisite. Seeds that become imbedded deeply in the g*rouna 

 do not vegetate, unless accidentally ploughed up, or exposed to 

 the atmosphere. Acorns, supposed to have lain for centuries, 

 have germinated as soon as they were raised sufficiently near 

 the surface to receive the influence of air. You will recollect, 



415. When do the seed leaves appear! 

 41G. When do the seed leaves decay 1 



417. What direction does the plume take? 



418. What effect has water upon the vegetation of the seed'? Is 

 earth essential to vegetation 1 



419. Is air nec.cssarv to 



