14 



FARMERS' REGISTER. 



[No. 1 



Chap. II. 



KLKMKNTARY STRUCTURKS OF PLANTS. VE- 

 GETAGLE MEMBRANE AND FJBRE. ELE- 

 MENTARV ORGANS OF PLANTS. CELLULAR, 

 AVOODYj AND VASCULAR TISSUES. 



If we examine a common plant, we find it 

 made up of roots, stems, leaves and flowers, or 

 fruit. These we term compound organs. If we 

 examine one of these, the stem for instance, we 

 tind that it is not a homogeneous mass, composed, 

 like a rock, of similar particles cohering together; 

 but that it consists oi" certain organized parts, in 

 the form of cellules and tubes. These we term 

 elementary organs, organic elements, or, taken 

 collectively, elementary tissues. The sides of 

 these cellules and tubes contain vegetable matter,^ 

 in what is believed to be its simplest condition of 

 organization. In this condition, it forms what 

 are ter(ned the elementary structures of plants. 

 Should we commence what might be called a 

 mechanical analysis of a plant, we would first ar- 

 rive at its compound organs; on analyzing these, 

 at its elementary organs, or organic elements; 

 and lastly, on analyzing these, at its elementary 

 structures. It will be necessary that we preserve 

 some order in our examination into the structure 

 and vital action of plants; and I do not know that 

 we can select any better than the one thus indi- 

 cated; commencing with the elementary struc- 

 tures, then taking the elementary organs, and, last 

 of all, the compound organs of plants. 



The elementary structures are but two; viz. 

 membrane and fibre. Vegetable membrane, when 

 ■examined with powerful microscopes, presents the 

 appearance of an exquisitely thin, transparent, co- 

 lorless film. In the living plant, it resists the ac- 

 rtion of water and watery solutions; but when lile 

 ceases, it is quickly acted upon by them, and re- 

 duced to a pulpy mass. Du Hamel, a botanist o( 

 just celebrity, supposes that vegetable membrane 

 is composed of small organic fibres, arranged par- 

 .allel to each other, and united by a jzlulinous sub- 

 stance. The Ihct that it tears with a ragged 

 ^cdge, as has been shown by Prof. Lindley, seems 

 10 Tavor this supposition. Yet as a matter of fact, 

 110 such structure can be detected by the micro- 

 scope; no traces of lines or nettings, or any thing 

 of the kind. On the contrary, it appears perlect- 

 iy homogeneous in its structure, resembling a 

 simple pellicle, or the film of a soap-bubble. In 

 jts simplest Ibriu, it composes the sides of the cel- 

 lules of cellular tisfeue; a little more condensed, the 

 sides of the sap-vessels; and still more condensed, 

 ithe general covering or outer skin of the bark. 

 Froiu the nature of vejretable membrane, perhaps 

 some may conclude, that it is not permeable to 

 duids; but such is not the fact. During the life 

 ■of a plant, both liquids and gases are passed 

 through it continually; as we shall see when we 

 comelo examine into the circulation of vegetable 

 fluids. Indeed, the film of a soap-bubble, to 

 which vegetable membrane was compared, al- 

 thouf'h in°ordinary circumstances, it resists the 

 passage of a gas— yet nothing is more easy than 

 to cau'se a gas to pass through it with great ra- 

 pidity; and'^thiB too, without tearing it, or injuring 

 il in the least. 

 The second of the elementary structures of ve- 



getables, is fibre. Vegetable fibre presents the 

 appearance of an exceedingly fine thread, resem- 

 bling the thread of which a spider's web is formed. 

 Any one who may have a curiosity to see it, can 

 have that curiosity gratified, by taking a leal-stalk 

 of a strawberry (Fragraria Virginiana) or what 

 is still better, of a common plantain (plantago lan- 

 ceolala^ and having broken it across, carefully 

 separating the two parts. The vegetable fibres, 

 which are coiled along the inside of the spiral ves- 

 sels of those plants, will uncoil in great numbers, 

 stretching like delicate threads, from one piece to 

 the other. Vegetable fibre does not enter as large-^ 

 ly into the structure of the elementary organs of 

 plants, as membrane. The principal parts com- 

 posed of it, are, what are termed spiral vessels. 

 These are either formed of it twisted in a spiral 

 manner, so as to form a tube, or else have it coil- 

 ed along their inner surfaces. It is not impossi- 

 ble, that both membrane and fibre, are composed 

 of a still more elementary structure. If we adopt 

 the notion of Du Hamel respecting the composi- 

 tion of membrane, this would seem very probable. 

 Nothing more would be necessary, than to give to 

 these constituent fibres, an arrangement some- 

 what different; placing them end to end, instead 

 of side by side; and vegetable fibre would be more 

 easily formed from them, than membrane itself. 

 Still this must be looked upon as nothing more 

 than a mere speculation; the microscope reveala 

 to us distinctly, the existence of membrane and fi- 

 bre; but beyond this it does not go. 



Pursuing our inquiry into the structure of plants, 

 the parts which stand next in simplicity to the ele- 

 mentary structures, are what are termed elemen- 

 tary organs. These appear in three ditierent 

 forms, viz., cellular, woody, and vascular tissues. 

 To these we will attend in the order in which 

 they have been mentioned. 



The cellular, or as some botanists term it, the 

 vesicular tissue, is the most abundant of the three. 

 If a transverse section of the elder (sambucus 

 canadensis) be examined with a good microscope, 

 it will present the appearance of a fine honey- 

 comb, made up of little hexagonal cells. If a 

 part of the same pith be boiled in water containing 

 a small portion of potassa in solution, it may be 

 separated into exceedingly minute bladders, by 

 rubbing it between the fingers. It was these 

 bladders, which, having been cut through, pre- 

 sented the honey-comb appearance noticed in the 

 first instance. In their natural state, they adhere 

 firmly to each other; but being boiled in a weak 

 solution of potassa, their adhesion is destroyed, 

 and they are set free. The pulp of the strawberry 

 consists of similar cellules; and in this instance 

 they adhere so loosely, as to be separated by sim- 

 ply rubbing the pulp under water. The cellules 

 in the pith of the elder are empty, those in the 

 pulp of a strawberry, are filled with a sweet red 

 liquid. The cellular tissue is made up of these 

 cellules, or little bladders, adhering together. 



In size they vary much in different plants, and 

 even in different parts of the same plant. Their 

 most common size is from 45.0 th to jij th of an 

 inch in diameter. From this they vary, so as to 

 measure in some instances 3V th, and in others 

 not more than y^Vo th of an inch in diameter, la 

 freneral, they are smallest in the leaves, larger m 

 The stem, and largest in the roots of the same 

 plant; and larger in succulent and annual plants, 



