]16 



MONTHLY JOURNAL OF AGRICULTURE. 



rise and distiibution of the sap, &c. So very 

 minute are the elementary organs of plants 

 individually, and so obscurely revealed are 

 their physical phenomena, even with Hie as- 

 sistance of the most jjovverful microscopes, 

 that few observers agiee in then* accounts of 

 either, beyond the admission of certain gen- 

 eral facts. 



The eimplest definable form of the vegetable 

 tissue or substance appears to be the cellular, 

 namely, tint presenting in division the angu- 

 lar meshes just referred to ; each of these 

 meshes is the section of a cell, consisting of a 

 very delicate triuisparent membrane, iiidi- 

 mentally globular, but assuming different 

 figures in consecpience of being pressed upon 

 by others in the growing plant ; when 

 equally pressed on all si<les by similar cells, 

 the globe becomes twelve-sided, and of the 

 form denominated by mathematicians the 

 rhomboidal dcxlecahedron, which being di- 

 vided in either direction, presents a hexagonal 

 outline, resembling the cells of a honey-comb ; 

 where the pressure is unecpial, the regularity 

 of the cells is variously aftected and distorted, 

 and they become more or less oblong and 

 rectangular, or present such a diversity of 

 figures in different plants, and in diffei-ent 

 parts of the same, that the delineation of them 

 would reipiire a far greater space tlian our 

 confined limits will admit, or the subject be- 

 fore us justify the dwelling upon, where a 

 hasty outline will answer the end proposed, 

 without entering into minutiie belonging to 

 the more abstruse and philosophical portion 

 of the science. Cellular tissue constitutes a 

 very considerable portion of the substance of 

 all plants ; the pith is wholly composed of it ; 

 so is by far the greater part of the bark, and 

 the external covering of the more delicate 

 organs; while, filling up the interstices left 

 by the disposition of the woody and other 

 tubular tissue, it seems to be almost analo- j 

 gou3 to fat in the animal economy, and, like 

 that, increases so much, unsler certain circum- 

 stances, as to alter materially the general as- 

 pect and condition of the plant ; it is indeed 

 that part of the vegetable fabric that is the 

 most iuHuenced by cultivation. The magni- 

 fied views in fig. 1 will convey some idea of 

 the arrangement of the cells, and especially 

 of the origin of their angular outline, which 

 is veiy beautifully seen by the assistance of a 

 microscope, or even by a good 77iagnifying- 

 glass, in a thin transverse slice of the stem of 

 the common raspberry, or that of any other 

 plant in which the pith ia not invested by a 

 very thick cylinder of wood. The size of 

 these little cells varies from the fiftieth to the 

 thon.sandth part of an inch in diameter, their 

 average bulk being about midway between 

 these estimates. In the earlier stages of their 

 existence they are filled with a fluid in which 

 a nuiltitude of little colored bodies, only visi- 

 ble under a vei^ high p(Aver of the micro- 

 scope, are seen floating with greater or less 

 rapidity— a phenomenon apparently as inti- 

 mately connected with that of vegetable life 

 (260j 



as are those of the lymphatic and arterial ca- 

 nals to animal existence. 



Cellular tissue has been justly denominated 

 the basis of the vegetable fabric. The sim- 



CEI.LULAR TISSUE. 



plest of all known plants exists as a single 

 globular or oval cell ; those a degree higher 

 on the scale are composed of similar cells, 

 more or less elongated and attached end to 

 end like the beads of a necklace ; then come 

 others more complicated by the attachment 

 of cells in breadth as well as length, the lower 

 or meaner of which present mere shapeless 

 or irregular masses, while the remainder of 

 the series, ascending by successive grades of 

 structure, may be traced by the eye of the 

 naturalist through a thousand varied and im- 

 provuig foi^ms, so beautil'ul, so admirably 



