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FERTILIZATION. 163 
honey. Those flowers which secrete nectar do so by means 
of nectar-glands, small organs whose structure is something 
like that of the stigma, situated usually near the base of the 
flower, as shown in Fig. 145. Sometimes the nectar clings in 
droplets to the surface of the nectar-glands ; sometimes it is 
stored in little cavities or pouches called nectaries. The 
pouches at the bases of columbine petals are among the most 
familiar of nectaries. 
201. Odors of Flowers. —The acuteness of the sense of 
smell among insects is a familiar fact. Flies buzz about the 
wire netting which covers a piece of 
fresh meat or a dish of syrup, and 
bees, wasps, and hornets will fairly 
besiege the window-screens of a 
kitchen where preserving is going on. 
Many plants find it possible to attract 
as many insect-visitors as they need 
without giving off any scent, but small 
flowers, like the mignonette, and night- 
blooming ones, like the four-o’-clock abe tie en eee 
and the evening primrose, are sweet- of the Grape (magnified), with 
scented to attract night-flying moths. # Boney-gland between each 
pair of stamens. 
It is interesting to observe that the 
majority of the flowers which bloom at night are white, and 
that they are much more generally sweet-scented than flowers 
which bloom during the day. A few flowers are carrion- 
scented (and purplish or brownish colored) to attract flies. 
202. Colors of Flowers. — Flowers which are of any other 
color than green display their colors to attract insects, or 
occasionally birds. The principal color of the flower is most 
frequently due to showy petals, sometimes, as in the marsh 
marigold, it belongs to the sepals, and not infrequently, as in 
some cornels and Euphorbias, the involucre is more brilliant 
and conspicuous than any part of the flower strictly so-called. 
