FLOWERS AND INSECTS 945 
During the day the small female Pronuba rests quietly 
within the flower, but at dusk becomes very active. She 
travels down the stamens, and resting on an open pollen 
sac scoops out the somewhat 
sticky pollen with her front legs 
(Fig. 239, A). Holding the little 
mass of pollen against her body, 
she runs to the ovary, stands 
astride one of the furrows, and 
piercing through the wall with 
her ovipositor deposits an egg 
in an ovule. After depositing 
several eggs in this way, she 
runs to the top of the ovary and 
begins to crowd into the funnel- 
shaped stigmatic cavity the mass 
of pollen she has collected (Fig. 
239, B). These actions are re- 
peated several times, until many 
eggs have been deposited and 
repeated pollination has been Fic. 240.—A mature capsule of 
effected. As a result of this, cet showing perforations 
made by larve of Pronuba in 
seeds are formed which develop _ escaping.— After Rizy and 
abundant nourishment for the  “"™®*™ 
moth larve, which become mature and bore their way out 
through the wall of the capsule (Fig. 240). 
147. Cross-pollination.—In those flowers in which cross- 
pollination is the rule, self-pollination is hindered in a 
variety of ways. In the cases about to be considered, 
stamens and carpels are together in the same flower; of 
course, in dicecious plants there can be no such thing as 
self-pollination. It is necessary to remember also that 
when the stigma is ready to receive the pollen, it excretes 
upon its surface a sweetish, sticky fluid, which holds and 
feeds the pollen, inducing the development of pollen tubes. 
