310 



HARDY FRUIT GARDEN. 



imperfect development of vascular and fibrous 

 tissue being discoverable in the form of a sort of 

 cylinder of bundles lying just in the centre. The 

 part within the cylinder, at its upper end, is now 

 the medulla, without it the bark ; while the cy- 

 linder itself is the preparation for the medullary 

 sheath, and consists of vertical fibres passing 

 through cellular tissue, and separates them hori- 

 zontally in every direction. 



" The young root is now absorbing from the 

 earth its nutriment, which passes up to the sum- 

 mit of the plant by the cellular substance of the 

 medulla, and is thence impelled into the cotyle- 

 dons, where it is aerated and evaporated : such 

 of it as is not fixed to the cotyledons passes down 

 through the bark into the root. The plumula, 

 forced onwards by the current of sap, which is 

 continually impelled upwards from the root, next 

 ascends in the form of a little twig, at the same 

 time sending roots in the form of fibres down- 

 wards in the centre of the radicle, which become 

 the earliest portion of wood that is deposited : 

 these fibres by their action now compel the 

 root to emit little ramifications. Previously to 

 the elongation of the plumula, its apex has ac- 

 quired the rudimentary state of a leaf ; this con- 

 tinues to develop as the plumula elongates, 

 until, when the first internodium of the latter 

 ceases to lengthen, the leaf has actually arrived 

 at its complete formation. When fully grown, 

 it repeats in a much more perfect manner the 

 functions previously performed by the cotyle- 

 dons ; it aerates the sap that it receives, and 

 returns the superfluous portion of it downwards 

 through the bark to the root ; it also sends fibres 

 down between the medullary sheath and the 

 bark, thus forming the first stratum of wood in 

 the new stem. During these operations, while 

 the plumula is ascending, its leaf forming and 

 acting, and the woody matter created by it 

 descending, the cellular tissue of the stem is 

 forming and expanding horizontally to make 

 room for the new matter forced into it ; so that 

 development is going on simultaneously, both in 

 a horizontal and perpendicular direction. This 

 process may not inaptly be compared to that of 

 weaving, the warp being the perpendicular, and 

 the weft the horizontal formation. In order to 

 enable the leaf to perform its functions of aera- 

 tion completely, it is traversed by veins origi- 

 nating in the medulla, and has delicate evapora- 

 tory pores (stomata), which communicate with a 

 highly complex pneumatic system, that extends 

 to almost every part of the plant. 



" The plumula having produced its first leaf, 

 others are successfully produced around the axis 

 at its elongating point, all constructed alike, 

 connected with the stem or axis in the same 

 manner, and performing precisely the same func- 

 tions as have been just described. At last the 

 axis ceases to elongate ; the old leaves gradually 

 fall off; the new leaves, instead of expanding 

 after their formation, retain their rudimentary 

 condition, harden, and fold over one another, so 

 as to be a protection to the delicate point of 

 elongation, or, in other words, become the scales 

 of a bud. We have now a shoot with a woody 

 axis, and a distinct pith and bark, and of a more 

 or less conical figure. At the axilla of every 



leaf, a bud had been generated during the growth 

 of the axis, so that the shoot, when deprived of 

 its leaves, is covered from end to end with little 

 symmetrically-arranged projecting points, which 

 are the buds. The cause of the perfect shoot 

 being conical is, that, as the wood originates 

 from the base of the leaves, the lower end of the 

 shoot, which has the greatest number of strata, 

 because it has the greatest number of leaves 

 above it, will be the thickest ; and the upper end, 

 which has the fewest leaves to distend it by their 

 deposit, will have the least diameter. Thus 

 that part of the stem which has two leaves above 

 it will have wood formed by two successive 

 deposits ; that which has nine leaves above it 

 will have wood formed by nine successive de- 

 posits, and so on ; while the extreme vital point, 

 as it can have no deposit of matter from above, 

 will have no wood, the extremity being merely 

 covered by the rudiments of leaves hereafter to 

 be developed. If at this time a cross section 

 be examined, it will be found that the interior 

 is no longer imperfectly divided into two por- 

 tions — namely, medulla and skin — as it was when 

 first examined in the same way, but that it has 

 distinctly two internal, perfect, concentric lines, 

 the outer indicating a separation of the bark 

 from the wood, and the inner, a separation of 

 the wood from the medulla : the latter, too, which 

 in the first observation was fleshy, and saturated 

 with humidity, is become distinctly cellular, and 

 altogether or nearly dry." Such is the first pro- 

 gress of a plant from seed. 



Air, moisture, darkness, and heat are all in- 

 dispensable in promoting germination ; the ab- 

 sence of them is the cause why seeds found at 

 greater depths in the soil than air penetrates to, 

 vegetate when brought within its influence, and 

 why they remained inactive during the period 

 of their being so deeply immured. What de- 

 gree of credence may be given to the asser- 

 tions of those who say they have caused to vege- 

 tate the seeds of wheat taken from the tomb of 

 an exhumed mummy, or of raspberry tarts being 

 made of fruit the produce of plants raised from 

 seed taken from a Roman barrow, we shall not 

 stop to investigate further, than by observing 

 that, if these facts are true, an absence of air, or 

 rather oxygen, was the cause of this long-sus- 

 pended vitality. That seeds do remain for a 

 number of years in a sound state when placed so 

 deep in the ground as to be beyond the influence 

 of oxygen, and probably an insufficiency of mois- 

 ture, is highly probable ; but there is a vast dif- 

 ference between a score or two of years and a 

 few thousands. 



When seeds are sown too deep, the effect is 

 that they germinate much slower than if placed 

 nearer the surface, and often, particularly in 

 damp soils and wet seasons, they perish alto- 

 gether. The following table was drawn up by 

 Petri : Of seed sown at the depth of \ an inch, 

 fths came above ground in 11 days ; at 1 inch 

 in depth, all came up in 12 days ; at 2 inches, 

 fths came up in 18 days ; at 3 inches, |ths came 

 up in 20 days ; at 4 inches, |ths came up in 21 

 days ; at 5 inches, fths came up in 22 days ; at 

 6 inches, |th came up in 23 days, — showing, 

 therefore, that shallow sowing is the best. 



