CHAPTER V 
PLANT-CELLS ; SOME FUNCTIONS OF CELLS IN THE ROOT 
57. Structure of a Plant-Cell.— Plants are made up of 
elementary organs called cells. These are small (usually 
microscopic) objects of many different shapes and subserve 
various purposes in the life of the plant. The simplest 
plants of all consist of but a single cell, which may have any 
one of a great variety of shapes, but is often nearly spher- 
ical. The higher plants, such as all the flowering plants, 
consist of hundreds of thousands or millions of cells each, 
and the total number in a large tree is inconceivably great. 
_A single cell taken from the tip of a 
growing shoot of any of 
the higher plants, when 
much magnified, is seen 
to consist of a cell-wall 
(wv, Fig. 20) filled with a 
more or less liquid sub- 
stance known as proto- Fie. 20. Two rapidly Growing Cells (both 
plasm. A large part of greatly magnified, A twice as much as B). 
the bulk of this proto- A is a very young cell in which the proto- 
: plasm does not as yet show vacuoles. B 
plasm consists of a is older, with several vacuoles; n, nucleus; 
roundish object Ns, called ne, nucleolus; cy, protoplasm or cyto- 
the nuel, eus, and inside plasm; v, vacuoles; w, cell-wall. 
this is a more opaque body ne, called the nucleolus. As 
the cell grows the protoplasm is soon found to separate 
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