Alfalfa seed production : pollination studies

According to Urban, the peculiar structure of the alfalfa flower by which it trips, or explodes, when visited by certain insects was known in the time of Linneus.The first explanation of the process of explosion is apparently that of De Candolle,' in 1832.De Candolle states that the explosion of the flower takes place when a certain stage of its maturity is reached.; Hildebrand," in 1866, gives a brief general account of the structure of the alfalfa flower, comparing it with both Indigofera and Cytisus.He clearly recognizes that the peculiar mechanism of the flower is an adaptation for pollination by insects, but states that inclosed flowers finally trip in the course of their development without the help of insects.Apparently he considers that fertilization may also take place in untripped flowers, as the pollen may fall on the stigma. His observations were made in Germany.In November, 1865, Henslow?presented a paper before the Linnean Society of London, which, however, was not published until 1867.Henslow studied carefully the structure of the alfalfa flower with a view of locating the explosive force.This he attributed to the elasticity of the stamineal tube, but he was uncertain whether the 1Candolle, A. P.de.Physiologie Végétale, t. 2, Paris,