THE GENERAL STRUCTOR 
E OF PLANTS 7 
certain cells of Tradescantia and Chelidoniwm, a similar 
streaming of the protoplasm is observable (fig. 8). Such 
Fig. 7.—CELLS FROM THE Lar Fic. 8.—Two CELLS FROM A 
or Elodea. x 3800. ‘STaMinaL Harr or Lrades- 
n, nucleus; p, protoplasm, in which 
cantia. x 800. 
are embedded numerous chloro- The arrows show the direction 
piasts. The arrows show the of the movement of the 
direction of the movement of the protoplasm. 
protoplasm. 
movements are spoken of as rotation when the current 
flows uniformly round the cell, or as 
path has a more complicated course. 
It has been mentioned that, 
with very rare exceptions, all cells 
contain a specially differentiated 
portion of protoplasm, known as the 
nucleus (figs. 6 and 9). This struc- 
ture does not occupy a very definite 
position in the cell, but not infre- 
quently is found almost in the 
centre. If the whole of the space is 
circulation when the 
Fic. 9.—NuceEus or a CELL, 
SHOWING ARRANGEMENT OF 
THE CHROMATIN THREADS. 
x 1000. 
not filled with protoplasm, the part 4 threads; b, nucleolus. 
in which the nucleus lies is con- 
nected with the lining layer by 
means of strands or 
bridles. In other cases the nucleus is embedded in 
