64 PRACTICAL BOTANY. 



Comparing their structure with that of sections of the stipe, 

 observe that the arrangement and character of the tissues is in 

 the main similar : observe further 



1. That there is no definite epidermis (compare Fucus). 



2. That the character of the cell-walls is like that in Fucus, 

 the middle lamella being swollen, and the pit-membranes highly 

 refractive. 



3. Where the section has traversed the margin of one of the 

 thong-like segments of the frond indications may be seen of their 

 separation from one another by rupture, since the tissues are 

 irregular at these points, and there is no superficial band as over 

 the rest of the surface of the thallus. 



Cut sections through the reproductive patches, and mount in 

 strong glycerine. 



Here the superficial cells are more elongated than in the 

 vegetative portion, thus forming a deep layer, in which two 

 different constituents are to be recognised 



a. Narrow club-shaped cells, with swollen walls : these are the 

 paraphyses, 



l>. Shorter cells, with thinner walls, and more oval form: these 

 are the "sporangia," the granular contents of which may be 

 seen to divide into a number of reproductive bodies, the further 

 development of which is unknown. 



