464 



F A li M E \i s ' u j: c; I s '1' e k . 



tNo.8 



in whose immediate neigiiborhood they <j:rovv, is not 

 mere imaginalion, it is nolhing more than a simple 

 Btalement of the tiicts of the car^e. 



It is a curious fact, llcquctitly noticed by bota- 

 nists, that plants in liieir wild sta'e, grow in natu- 

 ral groups. This is in part, to be ailril)uted to the 

 varying nature of the Foil, such plants as preler a 

 sandy soil, being collecied log(;ther where such a 

 Boil occurs; and in part abo to the Ofieralion ofthe 

 matter deposited by thern in the soil. Such plants 

 as deposite matter of a nature fiiteil to sustain and 

 assist each others growth, will generally be found 

 growing together. It would seem, that in parcel- 

 Jin"- oufthe earth, the creator has not assigned 

 particular species of animals alone, to particular 

 portions, and given them the means of defending 

 themselves against the aggression of their neigh- 

 bors; but that he had taken the same kind of care 

 for plants, at least to a certain extent. If a seed 

 of a plant which properly belongs to one portion, 

 is by accident, thrown upon another, the plants to 

 Avhich that portion belongs, soon destroy it. Thus 

 has the creator fixed for every separate portion of 

 creation, "the bounds of its habitation." 



Chap. XIX. 



EFFECT OF THK CHANGE OF SEASON UPON 

 A'EGETATON. POSITION OF THE SAP AT 

 DIFFERENT SEASONS. DRY-ROT — METHOD 

 OF PREVENTING IT. PROPER SEASON FOR 

 TRIMMING TREES. 



A periodical cessation of growth appears to be 

 necessary to the healthy action of most plants, 

 and in this particular we cannot but notice an ad- 

 mirable adaptation of the constitution of plants 

 to those changes of season, which, in some form 

 or another, are common to all climates. It is true, 

 that within the tropics, vegetation is not affected 

 by the alternate heat and cold experienced in ex- 

 tra-tropical regions; but yet, very much the same 

 effect is produced upon plants by the change li-om 

 the rainy to the dry season in those climates, as 

 by that from summer to winter in our own. The 

 effect of thedrysedson in the one case, and of win- 

 ter in the other, is not however to produce an entire 

 cessation of all growth; as it appears from experi- 

 ment that vegetation is at all times more or less 

 active; in the winter it is languid, whilst ii is ener- 

 getic in the spring and summer. The fact that the 

 buds of most plants swell, and that all plants form 

 additions of greater or less extent to their roots 

 during the winter, forbid us to entertain the idea 

 that there is a total cessation of vegetation at that 

 season. But although plants appear to have the 

 power of absorbing fluids by their roots during the 

 winter, they can have but little opportunity of 

 parting with any portion of it again by evapora- 

 tion, and as a necessary consequence, their tissues 

 become distended and turgid with the sap thus 

 accumulated. This turgidity of the tissues is at 

 its maximum just before the season at which 

 plants put forth their leaves, and is eminiently 

 favorable to rapid growth when vegetation re- 

 sumes its activity. "It is a well known flict, that 

 afler very long winters, or when a plant has been 

 prevented by artificial means from shooting at its 

 usual season, its branches and leaves are"'dcvel- 



oped with extraordinary rapidity," a circumstance 

 to be ascribed entirely to the accumulation of sap 

 in the tissues. 



The diurnal changes from light to darkness ap- 

 pear to be equally important to the well being of 

 plants with the aiuiual changes from summer to 

 winter. "If plants were kept incessantly grow- 

 ing in light they would be perpetually decomposing 

 carbonic acid, and would in consequence become 

 so stunted that there ;;ould be no such thing as a 

 tree, and this is actually the case in polar regions 

 where the day and night are each of six months 

 continuance. If on the contrary they grow in con- 

 stant darkness their liss'>es become excessively 

 lengthened and weak, no decomposition ol'carbonis 

 acid lakes place, none of the parts acquire solidity 

 and viffor, and finally they pensh. But in ordi- 

 nary circumstances, plants which in the day be- 

 come exhausted by the decomposition of carbonic 

 acid, and by the empt^'ing of their tissues by 

 evaporation, repair their forces at night by inha- 

 ling oxygen copiously, and so forming a new sup- 

 ply of carbonic acid, and by absorbing moisture 

 from the eartli and air without the loss of any por- 

 tion of it. Such being the case, we must conclude 

 that plants grow chieHy by day, and this is con- 

 formable to the lew observations which have been 

 made on this subject. Meyer Ibund that the Stent 

 of a belladonna lilly, and plants aC wheat and bar- 

 ley, grew about twice as liist by day as by nii^ht; 

 and Mulder states that he has arrived at similar 

 conclusions in watching the development of other 

 plants. 



When speakingof seeds and underground stems, 

 the fact was mentioned that the nutritive matter 

 which they contain, and which constitutes their 

 value as articles of food, is, in the economy of ve- 

 getable life, intended for the sustenance of the 

 young plants to which they give origin, durinir the 

 early stages ofthe growth of those plants, and be- 

 fore they have become sulficienily developed to ac- 

 quire nourishment lor themselves. The heart- 

 wood of trees appears to stand in a soaiewhat 

 similar relation to the young buds of a tree, serv- 

 ing during the winter as a depository for (he lurgiil 

 sap wliich the plant accumulated, and yieldinir it 

 up aijain, so soon as the flow of the sa|) has fully 

 commenced in the spring. The sap which accu- 

 mulates in the sugar maple (acer saccharinus) 

 during the winter, coiitains a large portion of sugar 

 in its composition; in the spring, as the watery 

 sap imbibed by the roots ascends the stem, it gra- 

 dually dissolves this sugar out from the heart-wood, 

 and carries it up lor the nourishment of the theii 

 swelling buds ; of course, the higher the sap as- 

 cends the stem, the more of this sugar will it have 

 dissolved ; and this is the reason why, it is found 

 necessary, in tapping that tree for the purpose of 

 obtaining sugar from its sap, that the openings 

 should fje made high up the stem, and not near 

 the root ; and further, that they should be made to 

 enter the heart-wood, and not lo pass through the 

 bark alone. I know that these fads respecting the 

 suirar maple have been adduced in support ofthe 

 idea that there is no such tliinix as a dowmvard 

 flow of the sap, and that its elaboration instead of 

 taking place in the leaves, takes place gradually 

 during its ascent ; but the downward flow of the 

 sap is established by so many incontrovertible 

 fiicts, that even if we could not give any explana- 

 tion of this matter, we could by no means admit 



