57i 



BOTANY. 



which will be adverted to hereafter; but, with these 

 exceptions, they may remain for ages uninjured. 

 They contain n vital principle or embryo, which, when 

 developed under favourable circumstances, is in all 

 respects like the parent, unless art has interfered to 

 change its form or qualities. When seeds are ripe 

 they are shed from the capsules or from the other 

 parts to which they were umbilically attached, and are 

 then covered with one, two, or three internments to 

 preserve them till the season arrives, when other 

 favourable circumstances conspire to produce germi- 

 nation. 



A perfect seed is one of the most wonderful produc- 

 tions in nature! It contains a living principle within an 

 organised body of cellular membrane capable of inde- 

 finite expansion. An acorn has been said to comprise 

 the rudiments of every member of the largest oak. 

 When placed in the soil, the fluids within arc excited 

 into fermentative action by the impact of heat, air, 

 and moisture, in due degrees. Expansion of the 

 membranes takes place, the outer coverings are burst 

 asunder, the rostel of the awakened plantlet escapes 

 away from dry air and light, descends in search of 

 humid and gaseous elemental food, and fixes itself in 

 the earth. Soon after the apex of the ascending axis 

 shoots upward, pierces the surface, and expands in 

 the air. 



The vital embryo is attached to one or two lobes 

 of nutritive matter, destined to yield sustenance to 

 the infant plant while it is establishing itself in the 

 ground. In doing this office these reservoirs of 

 nutrition either remain undeveloped in a shell, as the 

 cocoa-nut, within the surface of the ground, as the 

 common bean, or are raised with and upon the 

 ascending stem, as exemplified in the cucumber, the 

 garden balsam, &c. ; when thus developed they re- 

 ceive the name of seed-leaves (cotyledons). 



Were t conducive to any useful information, a 

 great deal of curious matter might be quoted here 

 relative to the growth of seeds, from their h'rst appear- 

 ance in the seed-vessel (ovanum), until the time when 

 they are ready to drop from it. Such investigations 

 have been made by botanical physiologists, who, by 

 the assistance of the microscope, have shown very 

 satisfactorily the progressive generation, or rather 

 gradual development, of seed, both before and after 

 impregnation ; but for such information we must 

 refer to those authors who have written on that 

 branch of botany called Carpology, and to the descrip- 

 tions and figures of the seed-vessels hereafter given. 

 Suffice to add here that the seeds of plants, like the 

 ovae of animals, are formed along with the vessels 

 which contain them, and of course long before im- 

 pregnation. 



The general form of seeds is ovular or kidney- 

 shaped ; some remarkably compressed, others de- 

 pressed, varying in size from an inch or more in 

 diameter to an atom hardly perceivable by the naked 

 eye. Some are provided with appendages for defence . 

 others with spiral awns, or little hooks, or wings, to 

 assist their dispersion. All are enclosed in a thin 

 film of cellular tissue, and this protected by a covering 

 of chaff, by a woody shell, or by a membranous or ! 

 leathery coat of dense cellular matter. These again 

 are frequently contained in pulpy, or fleshy, or rigid ! 

 vascular husks. When discharged from these integn- 

 ments they are of many different colours, as black, or 

 white, or brown of various shades, purple, and some 



are beautifully scarlet, and used as ornaments. Almost 

 all naked seeds have a mark or scar (Irilnni), sometimes 

 prominent or depressed on the exterior, showing where 

 they were attached to the seed-vessel or to its parti- 

 tions (dinm-piDicnts), or to the receptacle of the seeds. 



Although seeds, in all cases, are the real offspring 

 or progeny of plants intended for the perpetuation of 

 the species, and in this sense may be called also the 

 fruit of plants, yet botanists have made a distinction 

 between seed and fruit, and not without reason, be- 

 cause the latter is only the exterior covering of the 

 former. The mark of distinction is this : whenever a 

 stigma, or remains of its style, appears on the ex- 

 terior of any production succeeding the flower, it is 

 a fruit ; but if no such mark or remains of a faded 

 style be visible, it is a seed. By this rule, the com- 

 mon orchard apple, with the visible remains of the 

 flower at the top, and the dry leathery capsule of 

 the poppy, with its permanent stigma, on its apox, 

 are both fruits ; so the long husky pod of the common 

 broad bean, and the delicately beautiful pendent 

 globes of the cherry tree, are equally fruits. The 

 very large and very small seeds of the second and 

 third of these plants present no such exterior mark 

 or appendage at all similar. 



It has been already observed, that the internal 

 substance of some seeds are either farinaceous or 

 albugineous, and that these are destined for the 

 support of the infant plant (as the chick is in the egg) 

 before its roots are fully fixed in the ground. Such 

 substances are entirely absorbed by the plarif during 

 the first stage of its growth, and in but few instances 

 expanded as distinct bodies to do the office of leaves. 

 Other seeds are entirely filled, with the cotyledons 

 curiously folded up within the integuments, and when 

 set at liberty by the bursting of the shell, or outer 

 coat, they come forth in the air, expand, and seem- 

 ingly act like real leaves. They are, however, only 

 temporary appendages, as in most cases they quickly 

 drop off. 



The foregoing descriptions of seed relate only to 

 those plants called dicotyledons, that is, such as have 

 two seed-leaves, and monocotyledons, having but one 

 seed-leaf. But there is another class of plants, called 

 acotyledons, which have no seminal leaves, and con- 

 sequently the structure or organisation of their seeds 

 (sporules) are very different from those already men- 

 tioned. Instead of the resemblance to an egg, having 

 an embryo enclosed by, or surrounded with, farina- 

 ceous or albugineous envelopes, as in the dicotyle- 

 donous plants, they rather appear to be viviparous 

 particles separated from the mother plant, exserting 

 roots or shoots indifferently from any and every part 

 of them. But as these are only microscopic objects, 

 their modes of germination, or rather the manner of 

 their self-extension, is but imperfectly understood. 



The Root. A root is first an undivided spur-like 

 bod}', descending directly into the earth, either at- 

 tracted by its moisture or solidity, or averted from 

 dry air and light. The extreme point of a radicle is 

 elongated chiefly by the protrusion of its centre, and 

 in some degree by an increasing of its length, the 

 exterior cuticle being left behind, while the internal 

 part is momentarily progressing forward ; the point 

 itself being extremely delicate, would be instantly 

 checked or withered if exposed to dry air. This 

 constitutional delicacy may account for the prone 

 direction of roots in the first place, or at the first 



