322 THE BIOLOGY OF THE PLANT 



nules are found circular brown dots, the sori, each 

 of which, on being examined with a lens, is seen to 

 consist of a membranous expansion or indusium, 

 covering a group of small stalked bodies, the spo- 

 rangia, in which on microscopical examination 

 are found the spores. Among the bases of the 

 fronds of the current year will be found many- 

 dried stalks, the remains of leaves of previous 

 years. Upon removing the plant from the soil 

 and washing it in water it wiU be seen that the 

 leaves arise from a stem-like portion or rhizome, 

 which creeps along just below the surface of the 

 soil and gives off roots. 



5. Structure. — Remove a plant from the soil, wash the 

 roots, and study the following parts : 

 1. The rhizome. — "What is its general shape ? Does 

 it branch? Cut the rhizome across, midway 

 between its ends. What is the shape of the 

 outline? From what part of the rhizome do 

 the roots arise? From what part the fronds? 

 Are these positions constant ? Do you find any 

 other structures than roots and fronds borne 

 by the rhizome? Does the rhizome appear to 

 be made up of segments, as nodes and inter- 

 nodes? If so, how do you distinguish the 

 nodes ? On what part of the rhizome are the 

 leaves of the current year borne ? The remains 

 of leaves of past years? "What is the general 

 structure of that end of the rhizome which is 

 near the leaves of the current year ? What is 

 the color of the margin of the rhizome, as seen 

 in the cross-section? Of the greater portion of 

 its centre? Do you find near the centre any 



