GERMINATION. 



218 



GERMINATION. 



in the exhibition of bloom. It would 

 appear as if the vital force in plants was 

 not sufficiently powerful to carry on both 

 these functions simultaneously. At all 

 events, when one is most active, the other 

 is almost passive, and tho power of the one 

 is nearly always in the inverse ratio of the 

 other : hence, whatever favours the pro- 

 duction of wood (free, large potting, for 

 instance) is unfavourable to the produc- 

 tion of flower, and vice versti. 



Germination. 



In a state of nature all plants are propa- 

 gated from seed, and the multifarious forms 

 of the seeds and envelopes with which 

 they are provided form one of the many 

 interesting subjects of investigation to the 

 lover of nature. For the present purpose 

 it is sufficient to state that most seeds are 

 covered with a hard shell or envelope, 

 which protects them from external" injury, 

 and that within the envelope lies the 

 embryo plant. All seeds in this latent 

 state contain an organ, or germ, which, 

 under favourable circumstances, shoots up- 

 wards, and becomes the stem of the plant ; 

 another, called the Radicle, which seeks 

 its place in the soil, and becomes the root ; 

 and the seed-lobes, which yield nourish- 

 ment to the young plant in its first stage of 

 growth. 



Moisture, heat, and air are necessary 

 conditions for the development of all 

 seeds; and most of them require, in addi- 

 tion, concealment from the light. These 

 conditions are found in the open texture of 

 well-pulverised garden soil, through which 

 water percolates freely, and air follows, 

 each yielding their quota of oxygen, hydro- 

 gen, and carbon, in a gaseous state,, for the 

 support of the plant. The great majority 

 of plants cultivated in gardens are obtained 

 by sowing the seeds in beds suited to their 

 constitution, to be afterwards planted out 

 where they are to grow and ripen their 



fruits, or seeds, or leaves. Leaves are the 

 first outward sign of germination, and 

 throughout its existence, next to the roots, 

 the most important organ of a plant. The 

 seed-leaves, as the buds which first appear 

 above the ground are termed, arc of vital 

 importance to the plant, and if destroyed 

 prematurely, the young plant rarely re- 

 covers ; therefore, the leaves of all young 

 seedlings require protection from insects, 

 worms, and slugs, their most dangerous 

 enemies, as well as from severe weather. 



Germination, then, is the natural process 

 by which the embryo of the seed placed in 

 favourable circumstances that is to say, 

 surrounded by moisture and heat and 



FIG. I. DIAGRAM ILLUSTRATING GERMINATION 

 OF ACORN. 



shrouded in darkness throws off its shell 

 or covering, and in course of time becomes 

 a vegetable, resembling that from which 

 the seed was obtained. From the time 

 that the acorn of the oak is placed in 

 circumstances favourable to its germina- 

 tion, it absorbs moisture, the cotyledon A 

 (Fig. i) swells, the root or radicle P, i^ 

 elongated, and the shell or envelope c is 

 broken. The root issues by the fissure, 

 and directs itself downwards into the earth ; 

 the plumule D erects itself, is disengaged 

 from the shell, and becomes the stem, 

 while the cotyledons furnish food to the 

 young plant, until the first leaves develop 

 themselves and the spongioles of the roots 



