MARSILIA VliSTlTA. 205 



Figures 5 to 6. First divisions in the prothallium; in 5 this has taken place 

 in the ordinary way; in 6, the iirst division wail is verticalinstead of horizontal. 



Figure 7. Cross section of an older stage showing the first peripheral cell 

 which is already divided. 



Figures 8 and 9. Vertical sections of two young prothallia showing the 

 peripheral cells, and in 9, the basal cells. 



Figure 10. Two horizontal sections of a jirothallium of about the same age as 

 the one shown in figure 9. 



Figures 11 to 13. Stages in the development of the archegonium in vertical 

 section, n, neck; <, neck canal cell; b, ventral canal cell; o, the egg. 



In figure 12 the prothallium is seen in situ: k, the nucleus of the spore. 



Figure 14. A recently fertilized archegonium. 



Figures 15, 16. Young embryos in situ. 



Figure 17. Two cross sections of an embryo forty-two hours after the spores 

 were placed in water. 



Figure 18. Two longitudinal vertical sections of an older embryo; /, coty- 

 ledon; r, root; st., stem; /", foot. The apical cells are indicated by x, and the 

 age of the first walls is indicated by the numbers I and II. 



