OF DENISON UNIVERSITY. 
II3 
now opened, and the stigma laid bare to catch the pollen from the bee^s 
back, where it has been deposited by another flower, as previously de- 
scribed. 
The general arrangement for cross-fertilization in the florets of the 
Composite is the same as that just described for the Lobeliace^. But 
the vast number, the wide distribution, and the varied habits of the 
genera and species under the Compositae cause many special variations. 
These variations are shown especially by the arrangements of the hairs 
and the stigmatic papillae. In some genera, just as in the Lobelia, 
these hairs sweep the pollen before them, forming a simple ring around 
the style at the base of the stigmas or aggregated in a tuft at the ex- 
tremity of the stigmas. In other genera they spread over more or 
less of the surface of the style and the pollen is entangled among them. 
The mechanism for pushing out the pollen is farther perfected in some 
Composite by the contraction of the filaments of the stamens on being 
touched by the proboscis of the insect. 
