VII.] THE BRACKEN FERN. 55 



towards the free end, and there is nothing comparable to 

 the terminal bud of Chara with its numerous rudimentary 

 appendages. 



When the fronds have attained their full size, the edges 

 of the pinnules will be observed to be turned in towards 

 the underside, and to be fringed with numerous hair-like pro- 

 cesses which roof over the groove, inclosed by the incurved 

 edge. At the bottom of the groove, brown granular bodies 

 are aggregated, so as to form a streak along each side of the 

 pinnule. The granules are the sporangia, and the streaks 

 formed by their aggregation, the son. 



Examined with a magnifying glass, each sporangium is 

 seen to be pouch-shaped, like two watch-glasses united by 

 a thick rim. When ripe, it has a brown colour, readily 

 bursts, and gives exit to a number of minute bodies which 

 are the spores. 



The plant now described is made up of a multitude of 

 cells, having the same morphological value as those of Chara, 

 and each consisting of a protoplasmic mass, a nucleus and 

 a cellulose wall. These cells, however, become very much 

 modified in form and structure in different regions of the 

 body of the plant, and give rise to groups of structures called 

 tissues, in each of which the cells have undergone special 

 modifications. These tissues are, to a certain extent, recog- 

 nizable by the naked eye. Thus, a transverse section of the 

 rhizome shews a circumferential zone of the same dark brown 

 colour as the external epidermis, inclosing a white ground 

 substance, interrupted by variously disposed bands, patches, 

 and dots, some of which are of the same dark-brown hue as 

 the external zone, while others are of a pale yellowish-brown. 



The dark brown dots are scattered irregularly, but the 

 major part of the dark brown colour is gathered into two 

 narrow bands, which lie midway between the centre and 

 the circumference. Sometimes the ends of these bands are 



