MARCHANTIA. OOPHORE. 31 



consists of a wall (one layer of cells in thickness) 

 which surrounds and incloses a large, naked, nucleated 

 ovum. 



XIV. Cut vertical sections through a female branch 

 of like age to the above : treat as before, and observe in 

 median sections 



1. The stalk; on which is borne 



2. The terminal stellate head. 



3. That the latter consists of tissues similar to those 

 of the vegetative thallus : note especially 



a. The superficial " epidermis," and " stomata." 

 >. Air-cavities with chlorophylls-parenchyma. 

 c. Large mucilage-cells. 



4. The archegonia, which are flask-shaped bodies 

 suspended in an inverted position : note in a mature 

 archegonium 



a. The long neck, consisting of many tiers of 

 cells, which together form a single -layered 

 cylinder surrounding the channel of the 

 neck : when mature the neck will be seen 

 to be open at its apex. 



5. The more distended lower ventral part of the 

 archegonium, also surrounded by a single- 

 layered wall, and attached by a short massive 

 stalk to the receptacle. 



c. Pay special attention to the contents of the 

 ventral portion : in the mature archegonium 

 the cavity will be seen to be occupied by 

 a single primordial cell the ovum or 

 oosphere to which access is gained from 

 without through the channel of the 

 neck. 



