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timber trees, mingled with a great variety of those which are worthless, or fit only for 

 fuel. In some cases they are past redemption, having been so long neglected that they 

 have run up into mere thickets of hoop-poles. Young growth may everywhere be found, 

 however, which are in condition to be taken in hand, and in almost all cases the work of 

 thinning and pruning may be entered upon with a certainty of profitable results if wisely 

 and perseveringly conducted. 



The work of thinning, as ordinarily conducted in the occasional instances in which 

 on any account it has become desirable, is entrusted to mere labourers, who have no re- 

 gard for the natural conditions which are essential to healthy growth, and which can not 

 be suddenly changed, without serious injury to the trees that are left. 



All the small growth of shrubs, such as hazel, cornel, dogwood, elder, shad-bush, etc., 

 is first grubbed out and destroyed under the general term of "underbrush," and this not 

 only throughout the interior of the wood, but around its outer edges where such shrubbery 

 is apt to spring up in thickets, which serve the very important purpose of preventing the 

 free passage of the wind over the surface soil of the interior, besides adding incalculably 

 to the beauty of the wood, as seen from without by connecting the line of foliage of the 

 trees with that of the sward below, and presenting a living mass of verdure. The trees 

 which are considered most desirable to preserve are then selected, and all the rest at 

 once removed. Finally the leaves are carefully raked from the surface and carried off 

 or burnt. 



Sun and wind now have free access to the soil, and it very soon becomes parched 

 and dry. The fine rootlets near the surface, which have heretofore been preserved by the 

 never-failing moisture of the rich mould under its mulching of leaves, are converted into 

 a mass of wiry fibres, no longer capable of conveying nourishment, even if it were 

 within their reach. And while the means of supply are thus reduced, the tall, slender 

 trunk, through which the sap must ascend to the leaves, is now exposed to the free 

 action of the sun and winds. Now I do not presume to say that evaporation can take 

 place through the bark, but the provisions which nature makes to guard the inner vital 

 tissues from the effect of the sun's rays, indicate beyond all question that they are in 

 some way injurious. I have elsewhere shown that in the case of the single tree grow- 

 ing by itself, the trunk is always shaded by the spreading foliage, when suffered to retain 

 its natural form. In the forest the trees shade each other, and thus effect the object by 

 mutual action. But now let me call your attention to another provision of nature which 

 few people observe, but the meaning of which is too obvious to be mistaken. If we ex- 

 amine the bark of an oak, elm, chestnut or maple, of mature age, which has always stood 

 by itself, exposed to the full influence of atmospheric changes, we find it to be of great 

 thickness of very rugged character, and of a cork-like consistency, all of which character- 

 istics make it the best possible non-conductor of heat or cold that can be imagined, under 

 the protection of which the living tissues are safely kept from injury through the burn- 

 ing heat of summer and the intense cold of winter. 



Now go into the forest where the trees shade each other, and wind and sun are ex- 

 cluded, and you will find that the bark of the trees is smooth and thin in comparison with 

 that of those in the open ground. 



Nature never wastes her energies needlessly, and the trees in the woods do not re- 

 quire the thick coat of those that are exposed. But the effect of suddenly admitting the 

 sun and wind upon them is precisely the same as that of exposing any portion of the 

 human skin which had hertofore been clothed. It is to guard against injury from this 

 source that experienced tree-planters, when removing large trees from the woods, are 

 accustomed to swathe the trunks with ropes of straw, which is a rational process, yet it 

 is by no means uncommon to see the reverse of this action. I have seen during the 

 past winter a great many very large fine trees planted on the best avenues in Chicago, 

 at a cost of certainly not less than fifty dollars each, from the trunks and large limbs 

 of which all the rough bark had been carefully scraped, leaving only a thin, smooth 

 covering over the inner tissues. This is as if a man should prepare for unusual exposure 

 to heat or cold by laying aside all his clothing. 



Few persons, even among those whose business is tree culture, have any just con- 

 ception of the value of thorough mulching, as a means of promoting the health and 



