THE CELL. 



159 



granular appearance, and in the centre of each a rounded 

 denser portion may be made out, each of these again 

 enclosing one or more smaller bodies. This liquid which 

 thus fills the newly-formed cells is 

 ca>\]edprotoplasm; the large rounded 

 central mass is the nucleus, consist- 

 ing of denser protoplasm, and the 

 smaller enclosed masses are the 

 nucleoli. 



Now let us consider Fig. 219. 

 This is a representation of a section 

 of the same rootlet, taken a little 



Fig. 218. 



farther back from the point, so 



that the cells now in view are a 



little older than the first ones. 



They are manifestly larger ; that 



is to say,, they have grown. The 



nucleus and the nucleoli can still 



be made out in some of them, but 



the protoplasm no longer entirely 



fills the cell. There are now 



transparent spaces (vacuoles) 



which are filled with water, and 



between these the protoplasm is 



seen in the form of strings or 



bands, as well as lining the cell. Fig. 219. 



The water has been absorbed through the cell-wall, and 



after saturating the protoplasm the excess has formed the 



vacuoles. 



Fig, 218. Young cells filled with protoplasm (p) ; 6, cell wall ; h, nucleus : 

 kk, nucleolus. (Sachs.) 

 Fig. 219. Cells a little older, exhibiting vacuoles (s). (Sachs.) 



