CHARACE^ 213 



IV. The cells of the Characeae are well known as good 

 material for showing the movements of protoplasm in the living 

 cell : observations of this are to be made on living specimens 

 mounted in water. Nitella may be used, or the naked terminal 

 cells of the leaves of Chara. Note that the chlorophyll granules, 

 which lie in the outer band of protoplasm, are stationary : the 

 colourless protoplasm below shows however movements by which 

 the granules and clots are carried along, so that a rotation takes 

 place round the large central vacuole. If the movements be 

 sluggish they may be accelerated by gently warming the slide. 

 Note especially the movements in opposite directions on either 

 side of the neutral line, also the relative movements of the 

 contents of adjoining cells. 



V. In order to see the rhizoids, which fix the plant at its base, 

 remove one of the lowest nodes of an old plant : wash it gently 

 from mud, &c., and mount in water : numerous long, transparent 

 threads will be seen to spring from the node : these are the 

 rhizoids. Observe their smooth wall, and granular proto- 

 plasm with central vacuole, and the more dr less obvious 

 nucleus. Here and there they branch, the point of branching 

 being marked by an oblique, and peculiarly curved cell-wall : 

 from a swelling above the septum the branch-rhizoids spring. 



VI. The sexual organs are first to be examined in the mature 

 state : mount a leaf, bearing the bright scarlet antheridia, in 

 water, and examine under a low power. Note the position 

 at the node and below the oogonium : the spherical form, and 

 attachment by a very short stalk. Observe also the surface 

 markings, which indicate that the whole spherical wall is made 

 up of eight unicellular shields, of which the four upper are tri- 

 angular, but the four lower, adjoining the stalk, are four- 

 angled. 



Press gently on the cover-slip : the antheridium will burst, and 

 disclose numerous closely packed antheridial filaments ; each 

 of these is partitioned transversely into numerous disc-shaped 

 cells, and contains at maturity a single spiral spermatozoid : 

 the form of the latter can be clearly seen under a high power, 

 and under favourable conditions their escape as free, spirally 

 coiled bodies, with two cilia. 



