44 PISTILS AND STAMENS 
are three main structures involved in this development: (1) the 
fertilized egg; (2) the fertilized primary endosperm nucleus; 
and (3) the parts of the ovule surrounding the embryo sac. 
The development of each of these parts into their respective seed 
parts takes place simultaneously. The fertilized egg becomes 
the embryo, the endosperm nucleus has to do with the forming 
of the endosperm, and a part of the surrounding portion of the 
ovule becomes the seed coat. Figure 52 shows a Tomato ovule 
Fic. 53. — A young ovary of Corn just after fertilization and a mature 
ovary or kernel, both of which are sectioned lengthwise and the relation of 
parts indicated. A, lengthwise section of the young ovary showing nucellus 
(n), egg (e), endosperm nucleus (en), integuments (i), ovary wall (w), and 
base of style (b). B, the lengthwise section through the kernel showing the 
embryo (em), endosperm (end), seed coat (c), ovary wall (w), and the base 
of the style (b). The dotted lines indicate the parts of the ovule from which 
the different parts of the kernel have developed. 
in which the egg and endosperm nucleus have just been fertilized 
and also shows the seed which develops from the ovule. The lines 
indicate the parts of the ovule from which the different parts of 
the seed have come. Study Figure 53 showing the development 
of the ovule of Corn into a seed. Point out the different parts of 
the kernel and the part of the ovule from which they came. 
Notice that the heavy outer covering of the kernel is the ovary 
wall, and does not come from the ovule. A kernel of Corn is a 
seed closely jacketed by the ovary wall. Copy on a sheet of 
