The Sporing of the Fern 



255 



ion of the prothallus, the archegonia, which are the 

 reasons of their being. An archegonium also be- 

 gins life as a single cell, on the under surface of 

 the prothallus. A little later a crosswise parti- 

 tion appears, dividing the cell into an upper and 

 a lower portion. More par- 

 titions are formed, making a 

 cluster of cells, while the life 

 of the prothallus mould the 

 plastic young tissue till the 

 maturing archegonium takes 

 the shape of a flask, with a 

 proportionately very long and 

 thick neck, curved over to 

 one side (Fig. 70). 



The curve is generally in 

 such a direction that the 

 mouth of the flask points 



toward an antheridium. 



FIG. 70. Young archego- 



At first the flask S mouth nium of a garden maiden- 

 hair (Adiantum cuneatum). 



is closed, and its neck is (Much magnified.) 

 filled with a row of cells, called the " neck-canal 

 cells." But a little later these dissolve into muci- 

 lage, and at the same time the lips of the flask 

 draw apart. And from the flask's mouth, at this 

 date in its history, there is discharged an acid 



