9 2 



PART I. ORGANOGRAPHY. 



gynous. The Pinks, Gentians, many of the Composite, Umbel- 

 liferse and Labiatae, the Geranium, Mallow, and many Lobelias 

 and Campanulas are proterandrous. Figures 280 and 281 repre- 

 sent flowers of the common Pink, in different stages of develop- 

 ment ; in the former the stamens are ripe, and shedding their 

 pollen; while in the latter and older flower they are past maturity 

 and have withered, the expanded stigmas taking their place. It 

 is evident that an insect which has visited the younger flower, 

 and become dusted with its pollen, could hardly fail, when visiting 

 the older, to deposit some of it on the stigmas. 



Fig. 280. — Flower of Pink in the earlier or staminate stage of development. 

 Fig. 281. — Flower of Pink in the later or pistillate stage of development. 



Figs. 282 and 283 represent the proterandrous flowers of the 

 Great Willow Herb, Epilobium angustifolium. The mode of 

 cross fertilization is analogous to that of the Pink just described. 



In Fig. 282, the stamens, which are ripe and protrude from 

 the corolla, stand in such a position that an insect visiting the 

 flower for its nectar must touch them and receive some of their 

 pollen, but the style, crowned by the not yet unfolded stigma 

 lobes, is curved back out of the way. Later, as shown in Fig. 

 283, the stamens, having shed all their pollen, wither and curve 

 back upon the petals, while the style straightens out and the 

 stigmas unfold, occupying about the same position as the anthers 

 did before. It is clear that here, as in the Pink, an insect flying 



