STONEWORTS. 441 



examine it in water with a high power. Note 

 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 usu- 

 ally undergone fragmentation in cells in which 

 currents have commenced. The original nu- 

 cleus or the products of its division are passively 

 carried along by the currents. Sometimes it 

 is very difficult, on account of the incrustation 

 of the leaf-cells of Chara, to make out the proto- 

 plasmic movements in them; if this is found to 

 be the case, the manubrial cells from an anthe- 

 riditim 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 cell-wall, protoplasm, nucleus, and vacuolar 

 spaces. Note the protoplasm; partly forming 

 a layer (primordial utricle) lining the wall 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. Sometimes there are two currents in 

 opposite directions in the same strand. 



