DISCOMYCETES 311 



Endogenously formed antherozoids are differentiated from 

 the protoplasm of an antheridial cell, and eventually 

 escape through a pore at the apex of the cell. A 

 secondary division of the group having endogenously 

 formed antherozoids turns on the simple or compound 

 nature of the antheridium. A simple antheridium is 

 one in which each antheridial cell liberates its anthero- 

 zoids through its own special pore or opening. In a 

 compound antheridium several antheridial cells are so 

 grouped as to form a specialised organ, and discharge 

 their antherozoids into a common cavity, from which they 

 escape into the surrounding medium through a common 

 pore or opening. 



KEY TO THE FAMILIES 



GROUP I. Endogenae. Antherozoids produced endo- 

 genously. 



Antheridial cells united to form a compound anther- 

 idium. Monoecious or dioecious. Peyritschielleae. 



Antheridial cells distinct, discharging independently. 

 Monoecious or dioecious. Laboulbenieae. 



GROUP II. Exogenae. Antherozoids produced exo- 

 genously. Typically aquatic. 



Antherozoids exogenous. Zodiomyceteae. 



Peyritschielleae 



The principal morphological feature common to this 

 group, in which the antheridia are produced endogenously 

 within specialised cells or groups of cells, consists of the 

 fact that, however closely these specialised antheridial cells 



