METHODS 



2 9 



five to ten cells in thickness, enclosing the young sporophyte. With the 

 growth of the calyptra the unfertilized archegonia are carried up, some- 

 times appearing almost at the summit (Fig. 22, A). These sterile arche- 

 gonia may become much elongated and their necks twisted. 



Fig. 15. 



A. An old archegonium of Pallavicinia radiculosa, with much elongated neck. 



B. Surface of the upper part of a similar archegonium, showing the twisting of the 



neck. 



C. Young archegonium of P. Levieri, x 300. 



D. Apex of a somewhat older one, showing quadrant arrangement of the four 



terminal cells. 



E. Young archegonium of the same species. 



