44 PRACTICAL BOTANY. 



Mount specimens of antheridial branches from fresh 

 living material in sea-water, and having found an 

 antheridial branch exactly at the period of maturity 

 observe the partial disorganisation 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. 



IX. Having recognised 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 L structure of the thallus, which 

 bears 



2. Cystocarps of ovate form : these consist of closely 

 aggregated, small-celled tissue : they occupy the same 

 position as the lateral branches in a vegetative 

 thallus. 



3. Compare numerous specimens, and note cystocarps 

 in various stages of development. 



By careful observation on material taken in early summer the 

 various steps in the development may be traced, such as the 

 origin of the cystocarp as a multicellular body seated at a point 

 immediately below the apex of a short lateral branch of the 

 thallus, and recognised as a darker group of cells : the mode of 



