388 PRACTICAL BOTANY 



1. The normal structure of the main thallus. 



2. The club-shaped antheridial branches, often 

 associated together in groups : each consists of 



a. A unicellular pedicel, by which it is attached 



to the thallus. 

 5. A central linear series of cells, which is almost 



entirely hidden by 

 c. Numerous, closely aggregated, and small 



antheridial cells. 



Mount specimens of antheridial branches from fresh 

 living material in sea- water, f and having found an 

 antheridial branch exactly at the period of maturity 

 observe the partial disorganization of the walls of the 

 antheridial cells, and consequent liberation of their 

 protoplasmic contents, without subdivision, as round 

 non-motile spermatia. 



A comparison of numerous antheridial branches in various 

 stages of development will demonstrate that they originate from 

 single cells of the thallus, close to the apex of the branch : these 

 cells divide repeatedly by transverse walls, so as to form a linear 

 series, around which, in place of the normal pericentral cells, 

 antheridial cells are cut off by repeated longitudinal or oblique 

 divisions from all the cells of the linear series, except the basal 

 one, which remains as the pedicel. 



Transverse sections should also be cut through the antheridial 

 patches of Lemanea, when the antheridial cells may be recognized as 

 oval buds borne on club-shaped pedicels. 



IX. Having recognized a female plant by observations 

 with a lens on specimens taken in late summer or 

 autumn, mount a portion of it in glycerine, and, 

 examining it under a low power, observe 



1. The normal structure of the thallus, which 

 bears 



