( 337) 
toward the outside separate it from the epidermis and toward 
the inside from the more deeply lying tissue. The first tan- 
gential walls may be formed in this layer at the apex of the 
nucellus. 
The first suggestion of the origin of an integument is to be 
seen in the enlargement radially of the cells of the epidermis 
at two points, as appears in section not far removed from the 
apex of the nucellus. This collar-like growth is next aug- 
mented by a tangential division of the epidermal cells at its 
summit and later by the divisions of those beneath. The 
inner integument is clearly to be recognized before the outer 
one and rises above the nucellus as a thin collar two layers 
of cells in thickness and divided entirely from the epidermis. 
By the time that the inner integument has formed a distinct 
ridge around the young ovule, the expansion of the mass of 
tissue at its base denotes the beginning of the outer integu- 
ment. The growth of this integument soon exceeds that of 
the inner and before there has been much differentiation of 
structures within the nucellus it has far overtopped the inner 
integument and the nucellus. The ovule, in regard to the 
relative size of its different vegetative parts, is unlike that of 
other sympetalous flowers (Boraginaceae, Labiatae, Scro- 
phulariaceae, Valerianaceae, Compositae), in which there 
is a reduction of the nucellus and inner integument. In its 
earlier stages especially it bears far more resemblance to 
those of some of the Choripetalae (Rosaceae, Geraniaceae) 
than to those of other groups to which the Cucurbitaceae are 
regarded as more closely related. Figure 73 shows the rela- 
tive development of the different parts of the ovule. The in- 
teguments present the rather unusual appearance of bein 
much elongated and standing free for a considerable distance 
above the nucellus. The micropyle is a wide canal up to the 
time of fertilization and up to this time the inner integument 
is always distinct from the outer. Soon after this period, 
however, when there is the most rapid development of struc- 
tures within the nucellus, it becomes almost obliterated at 
the sides of the nucellus, though plainly visible toward the 
