PROPAGATION. 



65 



increase of various plants. These are, however, 

 auxiliary methods, wliich have been turned to ac- 

 count by the cultivator, the most general or normal 

 method being that of seeds or sexual increase. 



" A seed is a living body, separating from its 

 parent, and capable of growing into a new' in- 

 di\T.dual of the same species. It is a reproduc- 

 tive fragment, or vital point, containing witlnn 

 itself an the elements of life, which, however, can 

 only be called into action by s})ecial circumstances" 

 (Lindley). Every seed, from the tiny flour-like seeds 

 of Begonias, Grloxinias, kc, to the large seed or nut 

 of the Double Cocoa-nut, which is more than two 

 feet in diameter, and weighs over twenty pounds, 

 contains the beginning or germ of a plant, to- 

 gether with a certain quantity of food stored up 

 within it, and intended to supply the seedling with 

 nourishment till roots and leaves have been formed. 

 In botanical works seeds are divided into two great 

 divisions, according as thej^ have this nomishment 

 stored up (1) in the cotjiedons or (2) in the seed 

 itself. The first of these divisions is termed exalbu- 

 roinous, the second albumiuous. For all practical 

 pm-poses it is sufficient to define these terms as 

 meaning that the nutritive deposit for the seedling's 

 use is contained either in the first leaf or leaves of the 

 seedling itself, as in the Pea, Bean, Oak, Cucumber, 

 and the hke, or it remains in the seed after the 

 plantlet has grown out, continuing to suppl-y the 

 latter with food till it is strong enough to provide for 

 itself. The importance, therefore, of allowing the 

 cotyledons and seeds to remain on the germinating 

 plant till cast oS by the plant itself, is thus phiinly 

 shown. Numerous experiments made on germinating 

 seeds of Palms, Cycads, and other albuminous seeds, 

 and on various seeds belonging to the exalbuminous 

 division, such as Beans, Cucumbers, &:c., j)roved how 

 vitally important to young seedlings were their seeds 

 or the cotyledons respectively during the early stage 

 of development. By removing the seed of an Ivory- 

 nut {FhytelepJtas) and of a Cocoa-nut after germination 

 had taken j)lace, but before perfect leaves and strong 

 roots had been formed, death to the seedlings was the 

 immediate result. In the same way it was found that 

 by breaking away from seedling Beans and Cucum- 

 bers their thick fleshy cotyledons, the seedlings either 

 died at once, or were rendered incapable of developing 

 into healthy plants. 



AVhen a seed is placed under conditions favourable 

 to germination, it begins to undergo certain chemical 

 changes by the absorption of water and the effects of 

 heat, is softened, and becomes swollen, the germ or 

 embryo breaks through its shell, and a new plant is 

 thus bom. When once vitality is set in action in a 

 seed, its growth and development cannot be arrested 

 or prevented except by death. The root grows down 

 53 



into the earth, and that portion of the seedling 

 destined to form the stem grows in the opposite 

 direction. It is supposed that the force of gravitation 

 governs the growth of plants, but, whatever the cause, 

 all plants are governed by the same rule, sending 

 their roots towards the earth, and their stems or 

 leaves into the air. The amount of light, heat, and 

 moisture, and the nature of the soil that are most 

 suitable to the numerous and various forms of plant- 

 life may be considered under se^Darate heads. For 

 other conditions w^hich control germination the reader 

 is referred to the chapters on the Life-History of 

 Plants. 



Temperature. — The extremes of cold and heat 

 w^hich seeds are known to bear without any loss of 

 vital energy, although not without interest to horti- 

 culturists, need not be gone into here; those con- 

 ditions which are most favourable only being of 

 direct interest to us at present. It is not always safe 

 to turn to nature for information on how plants may 

 be best managed under artificial conditions. If we 

 could be sui-e that a certain natural method was 

 the best that nature employs, then probably to follow 

 her would be our wisest course. But nature, hke 

 gardeners, has often to have recourse to makeshift 

 plans. Plants are found growing under conditions 

 which do not more than supply the barest necessaries 

 of existence. There are numerous instances on 

 record of gardeners having been led astray through 

 copying what appeared to be nature's plan for the 

 management of certain plants. Orchids have been 

 found growing on the ground in moist shaded forests, 

 and it was, therefore, assumed that an imitation of 

 those conditions would be most suited to the plants 

 when cultivated in our houses. It was, however, 

 afterwards discovered that the plants found on the 

 ground had been blown down or otherwise removed 

 from their more favoured position on the tops of the 

 trees, where they were exposed to the fierce action of 

 an equatorial sun. In like manner seeds are found 

 germinating in all sorts of untoward situations. If 

 we consider for a moment how various must be the 

 conditions in which the seeds of plants are placed in. 

 a wild state, how they become widely disseminated 

 through the agency of birds, water, wind, (fcc, it is 

 easy to see how mistakes might be made if we were to 

 be guided in om' treatment of plants by our know- 

 ledge, often only very fragmentary, of how they some- 

 times exist in nature. 



Natm-e is a safe guide when we really understand 

 her. In the case of the Orchids above-mentioned she 

 showed us the best treatment for the plants. It was 

 the misjudgment of her imitators that led them 

 to look upon the Jirst conditions under which the 

 plants were found as the most suitable. ^Mistakes oi 



