Corda on the Impregnation of Plants. 319 
those of the great Englishman,* nor from the investigations of Mir- 
bel; but as we have to follow the course of the pollen-tubes into the 
innermost cavity of the ovules, it is necessary to be acquainted with 
their structure. 
Robert Brown was, we know, the first to demonstrate the pistillate 
flower in Conifere and Cycadee to be a naked ovule. This naked 
ovule is situated in a bottle-shaped cavity of the inside of the scale, 
which is directed downwardly and inwardly (‘Tab. 42, fig. 3, 6) and 
its first or outer coat (primine) (Tab. 42, fig. 3,c; Tab. 43, fig. 14; 
and Tab. 44, fig. 22, ccc) is coherent with the inner surface of the 
cavity ; therefore both together form the exostome, (Tab. 42, fig. 3, 
and 44, fig. 21, e’e’.) But this intimate union only exists in the 
early state ; they are gradually loosened by the ripening of the seeds, 
and at length the primine is completely separated from the walls of 
the cavity. While the inner side of the wall of the scale is being 
separated, a portion of the integuments of the scale tears loose, and 
appears like a wing half surrounding the base of the ripened seed, 
(Tab. 44, fig. 30, x. and 33.) 
During the ripening of the ovules, the exostome closes more and 
more, the primine gradually thickens, and becomes harder and almost 
corneous, and finally appears as a hard covering to the seed, (testa 
vel membrana externa seminis.) 
In an earlier stage, while the primine of the ovule is yet coherent 
with the surface of the cavity in the scale, we find in the upper part 
a free empty space, (Tab. 42, fig. 3, Tab. 43, fig. 14, and Tab. 44, 
fig. 21 and 22, ee’ c’c’) into which the summit of the (zapfenarti- 
gen) secundine (Tab. 42, fig. 3, 4, 5, Tab. 42, fig. 14, and Tab. 
44, fiz. 21—29) projects. This free space (which in the scale is 
under the ovule, the latter being suspended) is limited by the con- 
nexion of the secundine to the nucule and primine, (Tab. 43, fig. 
14, g.) 
The secundine (Tab. 43, fig. 14, dd) is a rather firm, hollow 
body, (zapfen,) which is connected with the nucule at the base, and 
terminated by its orifice at the other extremity. The nucule (f/f) 
of the ovules of Pinus is situated within the secundine, with which 
it is coherent only at the base. An exception which I have not 
previously observed in any other ovule. The secundineis originally 
a short conical body, in which a small, roundish, obscure spot makes 
* Robert Brown, Botanicorum facilé princeps— Trans. 
