THE GENEEAL STRUCTURE OF PLANTS 



neria, Nitella, Elodea (fig. 7), and others, a streaming move- 

 ment of the granules the protoplasm contains can be detected 



FIG. 7. CELLS FROM THE LEAF OF 

 Elodea. X 500. 



n, nucleus; p, protoplasm, in which 

 are embedded numerous chloro- 

 plasts. The arrows show the 

 direction of the movement of the 

 protoplasm. 



FIG. 8. Two CELLS FROM A 

 STAMINAL HAIR OF Trades- 

 cantia. X 300. 



The arrows show the direction 

 of the movement of the proto- 

 plasm. 



under a high power of the microscope. In other plants of 

 terrestrial habit, e.g. certain cells of Tradescantia and 

 Chelidonium, a similar streaming of 

 the protoplasm is observable (fig. 8). 

 Such movements are spoken of as 

 rotation when the current flows uni- 

 formly round the cell, or as circu- 

 lation when the path has a more 

 complicated course. 



It has been mentioned that, with 

 very rare exceptions, all cells con- 

 tain a specially differentiated portion 

 of protoplasm, known as the nucleus 

 (figs. 6 and 9). This structure does 

 not occupy a very definite position in the cell, but not 

 infrequently is found almost in the centre. If the whole 



THE CHROMATIN THREADS. 



X 1000. 



a, threads ; b, nucleolus. 



