IN OHCIlIDK.i:; AM) ASCIJ.FIADE.E. 505

of changes nearly ap;i'eeing \y[[\\ those wliicli M. Mir])eP has described and ilhistrated as taking place in other famihes.

In the earliest state in which I have examined the ovuluin in OrchidccT, it consists merely of a minute papilla pro- jecting from the pulpy surface of the ])lacenta. Ln tlie -703 next stage the annular rudiment of the future testa is visible at the base of the papilliform nucleus. The sub- sequent changes, namely, the enlai'gement of the testa, the production of a funiculus, which is never vascular, ancl the curvature or inversion of the whole ovulum, so as to ai)- proximatc the apex of its nucleus to the surface of the placenta, take place in different genera at different periods with relation to the development of the other ])arts of the flower. In general when the flower expands, the ovulum will be found in a state and direction pi'oper for receiving the male influence. But in several cases, as in Cypripedium and Epipactis, genera which in many other respects are nearly allied, the ovulum has not completed its inversion, nor is the nucleus entirely covered by its testa until lono- after expansion, and even after the pollen has been acted on by the stigma, and its tubes have penetrated into the cavity of the ovarium.

The tissue of the perfect stigmata in Orchidea^ does not materially differ from that of many other families. In the early state the utriculi composing it are densely approxi- mated, having no fluid interposed. In the more advanced but unimpregnated state, these utriculi enlarge, and are separated from each other by a co})ious and generally viscid secretion. The channel of the style, or stigma, whose parietes are similarly composed, undergoes the same chanoes. Both these states are represented in one of Mr. Bauer's plates, who however considers the more advanced staa'c as subsequent to imj)regnation.

In the advanced l)ut still unimpregnated state of the ovarium, the upper portions, which are in continuation with the axes of the three placenta\, but do not produce

yififu/i. (Jes So. Kat. xvii, p. 302 ;— aud in 2Iihii. de V Acad, des Sc de rinslit. ix, p. 212.

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