vi . ] STONE WOR TS. 53 



the superficial layer of protoplasm in which the 

 chlorophyll lies; it is stationary: focus through 

 this layer and examine the deeper one; note 

 the currents in it, marked by the granules they 

 carry along: their direction; in the long axis 

 of the cell, up one side and down the other, 

 the boundary of the two currents being marked 

 by the colourless band, in which no movements 

 occur. Try to find the nucleus ; it has usually 

 disappeared in cells in which currents have 

 commenced, but when present is passive and 

 carried along by them. Sometimes it is very 

 difficult, on account of the incrustation of the 

 leaf-cells of Chara, to make out the protoplasmic 

 movements in them; if this is found to be the 

 case, the manubrial cells from an antheridium 

 should be used instead. 



b. Tradescantia. Examine in water, with a high 

 power, the hairs which grow upon the stamens : 

 they consist of a row of large roundish cells, 

 each with sac, protoplasm, nucleus, and vacuolar 

 spaces. Note the protoplasm; partly forming 

 a layer (primordial utricle] lining the sac and 

 heaped up round the nucleus, and partly form- 

 ing bridles running across the cell in various 

 directions from the neighbourhood of the nu- 

 cleus, and from one part of the protoplasm to 

 another; observe the currents in these bridles; 

 from the nucleus in some, towards it in others. 



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 



