CRYPTOGAMS AND PHENOGAMS 507 
gametophyte, while the other is the essential part of a gamete. Here 
then is a gametophyte reduced to the simplest terms. The female 
gametophyte formed within the embryo-sac consists of a few cells 
forming two groups which lie at opposite ends of the macrospore. 
Those at the micropylar end (e7) include an egg-cell which is thus 
advantageously situated for fertilization by the pollen-tube entering 
the micropyle. The growth of the embryo from the fertilized egg- 
cell involves, as shown in Fig. 383, the formation of a suspensor (ef) 
which pushes the developing germ well into the mass of food. In 
this example the embryo comes to fill the sporangium completely 
while still attached to the parent, thus forming an exalbuminous 
seed, in which radicle, caulicle, and cotyledons are well developed. 
While it is not altogether clear how closed ovaries evolved 
from open carpels, the change may well have taken place 
as a result of the peculiar inrolling of the young leaf-lobes 
which primitive gymnosperms are supposed to have inherited 
from ferns. If ovules should form on such lobes while still 
inrolled, and the lobes should coalesce, the carpel would be 
angiospermic. However it happened, many highly important 
consequences of this advance are apparent. Most obvious 
is the greater protection of the offspring during the period of 
their dependence. 
There is also an enormous gain in possibilities for securing an 
advantageous cross. Thus a moist, projecting stigma becomes a 
target more likely to be hit by wind-carried pollen grains and more 
likely to insure their prompt germination, than the micropyle of 
a naked ovule. Expansion or branching of the stigma, such as 
we find to be characteristic of wind-pollinated angiosperms, shows 
how well this new organ lends itself to increasing the chances of 
pollination and at the same time favors economy in the amount 
of pollen produced. See Figs. 2-15, 27, 36,74 B, C, 109 C, D, 124 
B, 158, 159, 165 IJ, 171 IT, 248, 248, 254, 256 B, 257, 267 D, ete. 
A still further advance in these directions came when insects and 
other animals were attracted to the flowers, and their services thus 
secured as carriers of pollen. The attractive odors, bright colors, 
and alluring sweets, together with the marvelous arrangements of 
the various floral organs, present modifications of endless variety 
and offer one of the most fascinating fields in the whole range of 
botanical study. See Figs. 22, 39 IJ, 48, 57, 59 77, 80, 91-100, 106, 
133, 139, 145, 148, 156, 163, 164, 168 IJ, 172, 178, 187, 188, 189, 192, 
217, 251, 275, 276, 282-293, 299, etc. 
This elaborate modification of stem-parts and leaf-parts codperat- 
ing with pollen-sacs and ovules to form what we call a flower brings 
with it the further possibility of utilizing these accessory organs, 
