January 23, 1889.] 



Garden and Forest. 



45 



This transfer in our woody plants is effected wholly through 

 the younger woody part of the stem, as will presently be seen, 

 but in our herbaceous plants the transfer is through the cells 

 of soft tissues, especially those which are unhardened ele- 

 ments, answering to what is true wood in our woody plants. 



When a girdle of bark is removed from the trunk of a 

 forest tree the leaves remain for a time, frequently for a sea- 

 son, or even more, about as fresh as ever; but as the wood 

 begins to yield to the invasion of decay, the transfer of liquids 

 from the roots to the leaves is more or less completely 

 checked, and the tree dies. On the other hand, if, after having 

 built up a staging around a tree to give it enough support to 

 keep it in place, we should cut out all the wood of the trunk, 

 leaving the bark, the transfer of liquids from the roots 

 would be checked at once and the withering of the leaves 

 would follow in a single day. Thus, by these two experiments, 

 it is easy to prove that the path of readiest transfer of liquids 

 from the roots is in the woody part of a tree trunk. This 

 transfer is, in no sense, a circulation. 



Stomata, or breathing-pores of leaves. — The leaves are 

 practically continuous in their tissues with the fabric of the 

 twigs, and, therefore, with the branches and main stem, just as 

 the main stem is continuous with the main trunk and larger 

 divisions of the roots and these latter witli the rootlets. There 

 is an imbroken connection between the rootlets, with their 

 aljsorbing cells in the ground, and the thin tissvies of the 

 leaves exposed to tlie air. Now. from the thin tissues of the 

 leaves water evaporates. 



The external surfaces of the leaf are waterproofed by a 

 substance known as cutin, which covers every part of the 

 exterior, except at certain openings, chiefly on the under side, 

 known as breathing-pores or stomata. These are so numer- 

 ous in a single leaf as to be counted by hundreds of thous- 

 ands. 



They are, in fact, delicately-balanced valves of very minute 

 size, which are so perfectly governed in their working that 

 they can control the amount of water which is lost by evapo- 

 ration through the otherwise impermeable covering of the 

 leaf surface. The relations which these bear in point of num- 

 ber and niethod of construction to the peculiar surroundings 

 of swamp and desert plants, are among the most interesting 

 in the whole range of exquisite adaptations among plants. It 

 is enough to say, at present, that the amount of water lost by 

 evaporation, under ordinary conditions, is not larger than the 

 roots can readily supply. When a greater demand is made on 

 the roots than they can meet, the deficiency is revealed 

 promptly by the wilting of the lower leaves and afterwards by 

 those higher up on the stem. By this wilting the amount of 

 evaporation is temporarily lessened, and thus a chance is 

 afforded for the loss to be made good. 



Recalling what was pointed out in the third paper of this 

 series, namely, that the water throughout the plant is practi- 

 cally continuous, surrounding, as it does, in the form of films, 

 each structural molecule of the whole plant, the current of 

 water to meet that which is lost by evaporation through the 

 stomata is uninterrupted as long as the supply from the roots 

 holds good. But when the soil is relatively cold, the current 

 is checked and the leaves wilt, as can be easily shown by a 

 simple experiment. But the most common interruption is, of 

 course, caused by too great dryness of the soil. Soil may and 

 frequently does appear dry, and yet may have plenty of water 

 clinging to its particles, affording an adequate supply for the 

 plant, but when a certain limit of dryness beyond this is 

 passed, the plant feels it and shows it. By the wilting of the 

 lower and afterwards of the upper leaves, the evaporation is 

 checked, and unless the interruption is too long continued, 

 the current can be resumed when more water is supplied to 

 the soil. 



When a branch is cut off the current is arrested at once, and 

 is not resumed completely, even if the cut end is plunged 

 instantly in water. But it is an interesting fact that the leaves 

 keep fresh longer if the branch is cut off under zvater; in 

 this case, interruption of the current, even for an instant, is 

 avoided ; the continuity of the water system in the plant is 

 unbroken. It is possible, in this way, to keep some branches 

 fresh until decay of the cut surface begins. 



It is said by Mr. K. Miyabe to be a common practice in 

 Japan to cut with care flowering branches of ornamental 

 shrubs and trees for decorative purposes, and to char the cut 

 ends quickly and thoroughly before placing them in the water 

 of the vase. By this simple plan, which prevents the attacks 

 of fungi, causing decay, the branches remain fresh for a 

 longer time than in any other way. Repetitions of this prac- 

 tice in Cambridge, last summer, showed great differences in 

 this respect between different plants. 



A modification of the practice of cutting off branches under 

 water, to make them keep longer unwilted, is easily managed, 

 namely, by making a second cut after the piece is put in water. 

 The amount of water lost by evaporation differs according to 

 various circumstances, such as the temperature of the air, the 

 amount of moisture in the air, and so on, but the following 

 figures may lie of interest, although they are, at best, onlv 

 rough estimates. Professor Prestwich, quoted by Rolleston, 

 states that a tree of average size gives off two and one-half 

 gallons of water per diem. 



Hartig gives, as his estimate, about three pounds to an 

 average tree of twenty years' standing. 



Hales found that the Sunflower previously referred to in 

 this paper, gave off about a pound and a third everyday. 



Evaporation of water from the leaves concentrates the dilute 

 solutions of mineral matters brought up from the soil, (2) it 

 drains the soil to a certain extent, and lastly (3), it adds a cer- 

 tain amount of moisture to the air. But these effects on the 

 plant, the soil and the air have so many practical bearings, 

 that they must be deferred for special consideration. 



Cambrid.i<e, Mass. George Lincoln Goodalc. 



The Forest. 



The Forests and Woodlands of New Jersey." — II. 



A PURE FOREST.— There is a pure forest of Pitch Pine 

 -^^ {IHniis rigida) near Lakewood, in Ocean County, f The 

 trees are fifty or sixty feet higfi, and they average about ten 

 inches through. No underbrush grows among them, nor 

 anything but moss. The ground on which the}' stand was 

 culti^'ated a half a century ago, and this piece of forest shows 

 that under favorable conditions trees grow much faster than 

 most persons Ijelieve. The land here would have very little 

 value for any other use, and this is true of a great deal of land 

 in southern New' Jersey. It cannot be made sf) valuable 

 in any other way as by perpetuating forest growth upon it. 

 Few things would lie of greater benefit to this region than the 

 recognition l)y its land-owners of the fact that Pitcli Pine is a 

 good crop. 



Changes in the Woodlands. — There has not been much 

 change in the condition of the woodlands of New Jersey dur- 

 ing recent years, except what has been produced l)y the fluc- 

 tuation which is always going on in the local industries in dif- 

 ferent parts of the state. As a consequence of this fiuctuation 

 there is some variation in the market for fuel and other 

 products of the forest. In some districts of northern New Jer- 

 sey lime-burning has l)een actively carried on for the last few 

 }'ears, and wherever this is the case it creates a demand for 

 wood, which gives employment to many men as wood-cutters 

 and teamsters, and consideralile tracts of timber are cut oft' 

 which w'oidd otherwise be allowed to stand longer. The 

 profitalileness of forest-lands thus depends so largely upon 

 local conditions that no general statement can be made re- 

 garding it. The establishment of a lime-kiln or other wood-con- ■ 

 suming industry may render investments in forest-lands in its 

 immediate vicinity profitable when they would not have been 

 so without it. Considerafile movements of the population of 

 some portions of the mountain region in the northern part of 

 the state have sometimes resulted from such changes in local 

 industries which depend more or less directly on the supplv of 

 fuel and other forest-products. Between Deckertown and 

 Brick House, and in other parts of this hill-countr_\-, there are 

 hundreds of places still plainly marked by old Apple and 

 Cherry trees, or by the mounds where the chimne}'S have 

 crumbled down, where once stood the cabins of woodsmen. 

 A new forest growth crowds and chokes the fruit-trees 

 planted by these transient settlers, and vigorous Oaks and 

 Chestnuts are growing in the very places where once the fire 

 burned bright on the famil_\- hearth. An old resident of that 

 part of the state told me he remembered when those woods 

 were full of people, and mentioned having once been present 

 at a Democratic mass-meeting at a remote point which he 

 named, when there were hundreds in attendance; and he added, 

 by way of emphasis, "Where are those Democrats now ? " 



Beautiful Scenery. — There is a great deal of beautiful 

 scenery in northern New Jersey, and more and more of the 

 people of New York City will doubtless go to this region to 

 live. Many thousands of them have already established their 

 homes for the siunmer, or for the whole year, in the highlands 

 of this state which lie nearest the great town; but the move- 

 ment will go on increasing, and the beautiful hill-country, 

 which is still further awav, is certain to attract multitudes of 



*From advance sheets of the Report of the Geological Survey of New Jersey. 

 t^ An illustration of the Lakewood foiest appeared in this journal, on page 164 

 of Volume I. 



