PRO-EMBRYO 



217 



ovary, and conjugates with the ovum converting it into an 

 oosperm. 



After impregnation the ovary, with the contained oosperm, 

 becomes detached and falls to the bottom, when, after a 



ap.c 



term ~bvd 



rTi 



FIG. 50. Pro-embryo of Chara, showing the ovary (ovy) from the 

 oosperm in which the pro-embryo has sprung : the two nodes (nd) 

 apical cell (ap. c), rhizoids (r/i), and leaves (/) of the pro-embryo : and 

 the rudiment of the leafy plant ending in the characteristic terminal bud 

 (term. bud}. (After Howes, slightly altered.) 



period of rest, it germinates. The process of germination 

 does not appear to be known in Nitella, but has been followed 

 in detail in the closely allied genus Chara. 



The oosperm sends out a filament which consists at first 

 of a single row of cells (Fig. 50) giving out a root-fibre (rh) 



