442 ELEMENTARY LIOLOGV. [CIIAP. XIV. 



c. Vallisneria. Take a leaf beginning to look old; 

 split it into two layers with a sharp knife and 

 mount a bit in water ; examine with a high 

 power. Note the larger rectangular cells, be- 

 longing to the deeper layers, with well-marked 

 currents in them, which carry the chlorophyll 

 granules round and round inside the cell-wall. 



If no currents are seen at first, gently warm 

 the leaf by immersing it for a short time in 

 water heated to a temperature between 30" and 



J. Anacharis *. Take a yellowish-looking leaf: 

 mount in water and examine Avith a high power; 

 the phenomena observed are like those in Val- 

 lisneria. They are best observed in the single 

 layer of cells at the margin of the leaf. 



€. Nettle-hair. Mount an uninjured hair in water 

 with the bit of leaf to which it is attached 

 (it is essential that the terminal recurved part 

 of the large cell forming the hair be not broken 

 off); examine with the highest available power: 

 currents carrying along very fine granules will 

 be seen in the cell, their general direction being 

 that of its long axis. 



* Also called Elodca. 



