ANTHERIDIA OF MOSSES 279 



In some Liverworts {e.g. Fegatella) the groups of antheridia 

 are embedded in slightly thickened patches on the upper side 

 of the thaUus (Fig. 146, D, a.). A rather exceptional condition 

 obtains in Marchantia, wliere the thallus-lobe, in which the male 

 organs are sunk, is raised above the general surface on a definite 

 stalk (Fig. 146, F). Amongst the leafy forms the antheridia 

 are situated, either singly or in groups, in the axils'of the leaves. 



Fig. 153. — Vertical section through the antheridial head of the JIoss 

 Fiinaria, showing the antheridia (a.) and interspersed sterile hairs (p.). 



The antheridia of IVIosses show essentially the same structuie 

 as those of Liverworts, except that they are elongated and 

 possess a broader stalk (Fig. 153, a.). They occur m groups, 

 interspersed with multicellular sterile hairs (p.), at the top of 

 the stem or its branches. Each antheridial group is surrounded 

 by a number of spreading protective leaves {involucre), which 

 are not infrequently arranged to form a kind of cup, and usually 

 differ in shape and size, and sometimes also in colour, from the 

 ordinary leaves. The male plants of Mosses are thus easily 



