92 



Garden and Forest. 



[February 20, li 



This species does not exceed twelve Indies in height, and 

 does well in five-inch pots, making it a useful pot plant. £>. 

 plantagitietim cxcelswii is also showing flower-buds. This is 

 much taller in habit, and under liberal treatment it grows four 

 or five feet high, with (lowers four inches across. D. Anstri- 

 actun and D. Cbisii are equally desirable. After flowering in 

 pots the plants may be placed in the border for the summer, 

 and a second, and even third, crop of flowers will be produced 

 if the soil is rich and abundant water is supplied. ^^ ,^ , , 

 Passaic, N.J. -tS. Urpet. 



Principles of Physiological Botany, as Applied to 



Horticulture and Forestry. 



Mil. — The Changes which Organic Matter Undergoes in the 



Plant. 



THE preceding papers have outlined the mechanism by 

 which organic matter is formed by plants. It has been 

 shown that the green parts of plants possess the extraordinary 

 power of constructing out of inorganic materials, taken from 

 die air and soil, matter which is essentially like the very sub- 

 stance, of which both the framework and the living parts are 

 made. It is now necessary to see what are the changes by 

 which the simplest organic matter is transformed into various 

 complex substances found in the plant. 



For this examination a very brief review is essential. The 

 efficient agent in the change by which inorganic materials are 

 converted into organic matter is, as we have seen, the chloro- 

 phyll-granule (or its green pigment), which imparts to our 

 ordinary plants their characteristic color. In some striking 

 instances, this green color is hidden by other coloring matters 

 which occur either in the shape of granules or as dissolved 

 pigments ; but wherever a leaf accomplishes the work of 

 changing inorganic into organic matter, it does so through 

 the agency of its chlorophyll, or some equivalent of chloro- 

 phyll. Moreover, in these granules, or in the cells which con- 

 tain them, is effected also the equally important, but even 

 more mysterious, change by which nitrogenous compounds 

 are brought into combination with the simpler organic matter, 

 and the whole substance endowed with life. The absolute 

 necessity of sunlight, or light of substantially the same quality 

 as sunlight from some indirect source, in the first step in the 

 production of organic matter, has been commented on, but 

 attention must now be called to the fact that many, if not 

 indeed all, of the subsequent changes and combinations, can 

 go on without light. 



The radiant energy which falls upon the plant as sunlight is 

 received by the cells which contain chlorophyll, and in the 

 presence of the requisite inorganic materials upon which it 

 acts, is transformed into another form of energy, which is 

 retained. Chemically, this transformation in the plant always 

 accompanies reduction of highly oxidized compounds, in 

 which process a portion of the oxygen is released. The newly 

 transformed energy is now to be turned to other forms (or, as 

 one inay say, different kinds of work) within the plant. Putting 

 the same idea into the language of chemistry, we say that the 

 newly constructed organic inatter (formed by reduction from 

 highly oxidized materials, carbon-dioxide and water) is now 

 to be modified in many ways. But the principal ways are the 

 following : (i) the construction of new living mattter, (2) the 

 building up of new parts, including the repair of waste, and (3) 

 the performance of such kinds of work as lifting, and transfers 

 of all sorts. And when, after watching the expenditure of the 

 treasured energy, or the consumption of the stored-up organic 

 matters, we look at the ultimate products resulting therefrom, 

 there meet us only the inorganic materials with which we 

 started. In other words, we have followed the course of sun- 

 light in its marvelous activities, and have come back to the 

 point of departure. But between the first point, when we have 

 before us sunlight acting on the green plant containing chlo- 

 rophyll and employing carbon-dioxide and water in the pres- 

 ence of a small amount of dissolved earthy matter, as its raw 

 materials, to the last point, at which, after all the products have 

 been utilized and all the work done, we have only the raw ma- 

 terials back again, the distance is very great. Between these 

 points the changes may be simply innumerable. Their multi- 

 tude and complexity are best realized when we reflect upon 

 the diversified products of the vegetable kingdom which man 

 turns to account for his needs. All the timbers for shelter, the 

 fibres for clothing, the starches, sugars, oils, nitrogenous mat- 

 ters and condiments for food, the perfumes, the dye-stuffs, 

 • tanning materials, gums, resins, and drugs in general, form 

 but a small proportion, since these are only the very few of 

 which man has yet discovered the uses and employed for his 

 wants. Their multiplicity is so great that only a few character- 

 istic changes of a general nature can be selected for pres- 



ent observation. For this purpose, in our hasty glance at these 

 changes, or what is called metastasis, or metabolism, we must 

 note that there is a building up, and there is likewise a pulling 

 down — a treasuring and an expenditure of energy ; and one of 

 these is discernible in all the greater changes which go on within 

 tiie plant. But there are a few changes which appear to be on 

 a single plane, that is, there is no marked modification in the 

 chemical composition of the materials, but simply a re-arrange- 

 ment of their constituent atoms. In the plant, constructive 

 metabolism, in its widest sense, includes the storing up of 

 sunlight and the subsequent utilization of the formed materials 

 in the making of new parts ; on the other hand, destructive 

 metabolism includes all those retrograde changes in material 

 by which the stored energy does any sort of work. 



For convenience it is well to look first at the organic pro- 

 ducts which contain no nitrogen. These may be roughly 

 grouped into three classes, (i) the carbo-hydrates, (2) the fats, 

 and (3) the vegetable acids. 



I. The carbo-hydrates are of two general sorts, (i) the starch 

 group and (2) the sugars. Starch is the first visible product of 

 assimilation proper; that is, it is the first substance which 

 we can detect as a solid in the assimilating cells, but in all 

 probability it is not first body formed ; it is likely that some 

 form of sugar is the primary substance produced in the work 

 of a green leaf . Starch has the same elementary composition 

 as cellulose or cell-wall material, but its physical characters 

 and chemical reactions are different from those of cellulose. 

 Under certain circumstances cellulose may be employed as 

 food by the seedling; but such cases occur only in instances 

 like that of the hard seeds of dates, etc,, in which there is also 

 a further supply of more easily utilizable food. Cellulose is 

 used for building, not as food. Starch, on the other hand, is 

 one of the principal forms in which food is treasured by plants. 

 It is accumulated in underground parts, as roots and tubers, 

 and above ground in leaves, stems and seeds, taking on char- 

 acteristic shapes and markings. In many instances these dis- 

 tinctive characters enable one, by the use of the mi jj oscope, 

 to detect cases in which starch from one source has been sub- 

 stituted by accident or design for another sort. One of the 

 most interesting discoveries of modern times is the fact that 

 these grains of starch accumulate through the intervention of 

 colorless granules of living matter, which, as shown in the first 

 paper of this series, are substantially the same in origin as the 

 chlorophyll, or green granules, by which oi:ganic matter is 

 constructed under the influence of sunlight. 



There are iTiany substances which are identical in atomic 

 composition with cellulose and starch, namely, inulm, or the 

 substance in which much of the food is stored in certain plants 

 of the Sunflower Family, and dextrin, which occurs in much sap 

 at the time when rapid building of new parts is going on. To 

 the same group belong certain gums — for instance, Gum Ara- 

 bic. These which we have mentioned are only a very few of 

 the bodies allied to cellulose which are found in plants, but this 

 brief reference to them may indicate the importance of the 

 fact that out of precisely the same proportions of three ele- 

 ments, viz., carbon, oxygen and hydrogen, it is possible to 

 derive substances so diverse in their appearance and physical 

 properties. By comparatively slight changes in the chemical 

 composition these are transformed into other substances, which 

 will be discussed in the next paper. 

 Cambridge, Mass. George Lhicoln Goodale. 



The Forest. 



Forestry in New England. 



THE extracts v\^hich follow are from an address 

 delivered before the Massachusetts Horticultural 

 Society, at Boston, on February 9th, by Mr. J. B. Harrison, 

 Secretary of the American Forestry Congress : 



New England has in her own territory a conspicuous 

 illustration of the value of an extensive tract of. mountain 

 forest, and of the evils which result from the destruction of the 

 woods. The White Mountain region of New Hampshire was, 

 in its natural condition, remarkable for the amount of beauti- 

 ful scenery in a limited area — that is, for the number, interest 

 and variety of its separate, complete landscapes. Each pic- 

 ture or scene was large enough to make the impression of 

 individual and satisfying beauty, and there was little waste 

 space between them. There was merely for each one a 

 natural and charming frame. 



I have time to-day to mention but one of the functions of 

 this mountain forest — that of a place for summer rest and 

 recreation ; for sylvan peace and shade, coolness, beauty and 

 refreshing change for men and women weary of the heat 



