FIG. 309. Development of the ovule and embryo of the shepherd's 



purse (Capsella) 



A, young ovule, showing origin of two integuments at base of nucellus n. B, outer 

 integument growing beyond the inner, and the ovule beginning to bend over: 

 es, embryo sac. C, diagram of a later stage with mature embryo sac. D, devel- 

 opment of the suspensor s. E, early divisions of the terminal cell (embryo 

 cell). F, later stage, showing the differentiation of an outer cell layer in the 

 embryo, which is to become the epidermis. G, the two cotyledons c and the 

 root region r now clearly defined. //, lengthwise section of an ovule, show- 

 ing the position of an embryo in an embryo sac: em, embryo; s, suspensor; e, 

 endosperm; ii, inner integuments; oi, outer integument; m, micropyle. A, 

 B, C, adapted after Campbell 



386 



