FORMS OF CELLS. Lit 
II. Forms of Cells. 
Notwithstanding the unlimited variety of forms of developed 
plant cells, they, nevertheless, show very similar outlines in a 
young condition. In every case where cells can develop unob- 
structed, they assume a spherical shape (Fig. 80), which is the 
fundamental form of all cells (Saccharomyces, spore cells, pollen, 
heads of glands, the cells of soft tissue, for instance, of the 
medulla). 
The subsequent distinctions in form are produced either 
through unequal surface growth, or growth in thickness or 
length of the cell, or through the pressure of contiguous cells. 
Fia. 80. Fie. 81. 
Fic. 80.—Spheroidal cells. Isodiametric parenchyma. 
Fig. 81.—Parenchymatous tissue from the pith of the Hider. 
If the surface growth does not proceed uniformly, there are 
formed a great variety of elliptical, tabular or hemispherical, 
sinuate, star-shaped (Fig. 152) or plaited cells. 
If the growth in thickness is unequal, all the forms are devel- 
oped which have previously been mentioned when considering 
the growth in thickness of the membrane (page 149): the 
pitted, scalariform, annular and spirally thickened cells (vessels, 
Figs. 66 and 68), the stone-cells and bast-cells (sclereids,” 
Figs. 70, 110, 115, 116, 117). If the growth in thickness is 
confined to the corners, collenchyma is formed (Fig. 109 4). 
If the growth in length is unequal, that is, chiefly confined 
to two opposite sides, there are produced elongated forms of 
1 See page 156, foot note. 
