84 
one is through the hairy throat. The force which raises the 
seeds from the bottom of the calyx is centrifugal, created by 
rapid spring-like movements of the stiff flower stalks; and on any 
windy day if numerous heads be examined, seeds may be found 
wedged among the stiff hairs of the calyx throat, unable to es- 
cape. These bristles are capable of rapid hygroscopic move- 
ment ( Figs. 29-30). 
While searching for examples of seed distribution, attention 
was called for the first time to the richly endowed disbursive 
powers of Polygonum Virginianum (Figs. 38-43). The two long 
reflexed styles of this plant, which are notably persistent, are 
extremely elastic when dry and at the same time arranged in 
such relations to each other, that they form an inverted wedge- 
shaped space capable of holding, when once inserted, the hair of 
any passing animal. If slight pressure is brought to bear upon 
the under side of these strong, persistent styles, the seed suddenly 
separates from its pedicel and flies to the distance of several feet 
from the plant. The seed in its passage through the air follows 
a continuous path without revolutions on its own axis. 
DESCRIPTION OF FIGURES. (Plate CXVI.) 
No, 1. Campanula Americana. Dry. 
No. 2. The same thirteen minutes after immersion in water. 
No. 3. Veronica Virginica, Dry. 
No. 4. The same moistened. 
No. 5. View from above of dry capsule. 
No. 6. Syringa vulgaris. Dry. 
No. 7. The same moistened. 
No, 8. Side view, showing seeds a. 
No. 9. Stetronema longifolium. Dry. 
No. 10. The same fifteen minutes after being placed in water. 
No. 11. Green pod of Claytonia Virginica, seen from above. 
No, 12. The same dry, after seeds have been thrown. 
No. 13. The pod ready for dispersion of seeds: a, 4, and c, seeds first, second, 
and third, in order of expulsion. 
No. 14. Side view of pod after expulsion of the seeds, 
No. 15. Side view of seed. 
No. 16. Hybiscus Syriacus. Dry. 
No. 17. Same in water fifteen minutes. 
No. 18. Hypericum Ascyron, Dry. 
No. 19. Same in water five minutes, 
No. 20. Cassia Chamecrista, Dry. 
No, 21, Same immersed in water six minutes, 
