MICROSCOPE IN THE GARDEN. 17 



it under the Microscope, the cellular structure of 

 plants may be observed in all their soft parts. 



If, now, we take a thin section from an apple, or 

 other soft fruit, or from a growing bud, or tuberous 

 root, as the turnip, we shall find that many of the 

 cells contain in their interior a " nucleus," or 

 central spot (Fig. 1, PL 1). This nucleus is a 

 point of great importance in the history of the 

 cell, for it has been found that the cell originates 

 with it, and that all cells are either formed from a 

 nucleus of this kind, or by the division of a thin 

 membrane in the interior of the cell, which repre- 

 sents the nucleus, and is called a " primordial 

 utricle." 



When the cells of plants have thus originated, 

 they either remain free or only slightly adherent to 

 each other, or they press upon each other, assuming 

 a variety of shapes ; they then form what is called 

 a " tissue." When cells are equally pressed on all 

 sides, they form twelve-sided figures, which, when cut 

 through, present hexagonal spaces (Fig. 2, PL 1). 

 This may be seen in the pith of most plants, more 

 especially the common elder. Transverse slices 

 of the stems of any kind of plant from the 

 garden may be made by a razor, or sharp pen- 

 knife, and will afford interesting objects for the 

 Microscope. 



Cells, during their growth, assume a variety of 

 shapes, and the tissues which they form are n'amed 

 accordingly (Figs. 232, 234, PL 8). Sometimes the 

 cells are very much elongated, or they unite together, 

 to form an elongated tube : the tissue thus formed is 

 called " vascular tissue ;" but where the cells retain 

 their primitive form, it is called " cellular tissue." A 

 very interesting form of the latter is the " stellate" 

 tissue found in most water-plants, and especially 

 regularly developed in the common rush (Fig. 3, 

 c 



