410 PRACTICAL BOTANY 



Fresh material should be used if possible ; most of 

 the structural points can, however, be successfully ob- 

 served on material preserved in alcohol. 



I. Examine a mature specimen of Chara with the 

 naked eye, or with a pocket lens, and note 



1. The stem, which is as thick as coarse pack- 

 thread, and is marked off into internodes of length 

 varying from 1 to 3 or 4 inches : this axis is of 

 unlimited growth, and is terminated by an apical 

 bud. 



2. The "leaves" or branches of limited growth, 

 which are arranged in whorls, the point of insertion 

 of each whorl being recognized as a node : the 

 number in each whorl may vary. Examine the leaves 

 with a lens, and observe that they also show a 

 distinction of nodes and internodes ; in some species 

 whorls of small unicellular outgrowths (leaflets) may be 

 seen at the nodes : thus the leaves repeat the characters 

 of the axis on a smaller scale. 



3. In the axil of one leaf in each whorl is usually 

 found a branch of unlimited growth, which repeats 

 all the characters of the main axis. 



4. Examine the base of the plant where it is fixed in 

 the mud : very long transparent rhizoids may be seen 

 to be inserted at the nodes. 



5. On the inner side of the leaves of plants taken in 

 summer or autumn the sexual organs will be found, 

 viz., the antheridia, which are globular and of a red 

 colour, and the oogonia, which are of a dark olive 

 colour or brown : these sexual organs are seated, in the 

 monoecious species, in pairs, at the nodes of the leaves, 

 and on the inner, adaxial, side of them. 



