all were observed excepting a3, which is the most difficult one to trace, and apparently is oftenest absent. In the Cypripedeæ, again, all were traced except a3,[1] which, I feel pretty sure, was here really absent: in this tribe the stamen (A1) is represented by a conspicuous shield-like rudiment, and a1 and a2 are developed into two fertile anthers. In the Ophreæ and Neotteæ all were traced, with the important exception of the vessels belonging to the three stamens (a1, a2, and a3) of the inner whorl. In Cephalanthera grandiflora, I clearly saw a3 proceeding from the anterior ovarian group, and running up the front of the column. This anomalous Orchid has no rostellum, and the vessel marked Sr in the diagram was entirely absent, though seen in every other species.
Although the two anthers (a1 and a2) of the inner whorl are not fully and normally developed in any Orchid, excepting Cypripedium, their rudiments are generally present and are often utilised; for they often form the membranous sides of the cup-like clinandrum on the summit of the column, which includes and protects the pollen-masses. These rudiments thus aid their fertile brother-anther. In the young flower-bud
- ↑ From Irmisch's ('Beiträge zur Biologie der Orchideen,' 1853, pp. 78 and 42) description of the development of the flower-bud of Cypripedium, it would appear that there is a tendency to the formation of a free filament in front of the labellum, as in the case of Glossodia before mentioned; and this will perhaps account for the absence of spiral vessels, proceeding from the anterior ovarian group and coalescing with the column. In Uropedium, a genus which A. Brongniart ('Annal. des. Sc. Nat.,' 3rd series, Bot. tom. xiii. p. 114) considers closely allied to, and even perhaps a monstrosity of, Cypripedium, a third fertile anther occupies this same position.
supplying the fertile anther runs up the connective membrane between the two anther-cells, but does not bifurcate: the vessel to the rostellum runs up to the top of the shoulder or ledge beneath the connective membrane of the anther, but does not bifurcate and extend to the two widely-separated viscid discs.
