22 PRACTICAL BOTANY 



2. The layer of protoplasm (primordial utricle), which lines 

 the cell-wall. 



3. The red cell-sap filling the cavity of the cell (vacuole). 

 Note that the red sap does not escape from uninjured cells. 



a. Examine a similar section which has been dipped for a 

 moment into alcohol, and thus killed ; the red sap diffuses out 

 of the cells : hence it is evident that though the colouring-matter 

 does not diffuse out of a living cell, it diffuses readily out of a 

 dead cell. 



b. Mount another section in water, and run some 2^ per cent, 

 salt solution under the cover-slip ; it will be seen that the red 

 sap collects as rounded deeply-coloured bodies in the centre of 

 the cells. This is due, as in the previous cases, to the contraction 

 of the primordial utricle. Wash out the salt solution with 

 water, and some at least of the plasmolyzed cells will gradu- 

 ally reassume their original appearance. 



IV. In order to observe the movements of protoplasm in the 

 living cell, mount in water a rootlet of Trianea Bogotensis, or, 

 if that be not available, of Hydrocharis morsus-rance ; in fact, 

 any plant in which the root hairs can be obtained free, and 

 uninjured, will do, aquatic plants being most suitable : examine 

 first with a low power, . and note the solid cylindrical body of 

 the root with its conical apex : its surface is studded, except 

 near to the apex, by transparent cylindrical out-growths the 

 root-hairs. Neglecting the body of the root, focus under the 

 high power upon one of these hairs, and observe 



1. The thin, smooth cell-wall. 



2. The granular protoplasm constituting the primordial 

 utricle which lines it, and surrounds the large central vacuole, 

 from which it is separated by an irregular inner surface. 



Focusing carefully upon the granules in the protoplasm, 

 these may be seen to be in motion, being carried along by a 

 streaming movement of the protoplasm (rotation). By gently 

 warming the slide on the palm of the hand, or over a lamp, the 

 movement may be accelerated. 



Heat the slide over a spirit-lamp to boiling point : the move- 

 ments will, on examination, be seen to have stopped, the cell 

 having been killed by the high temperature. 



