observation were necessary, succeeded in ascertaining the
very general existence of the foramen in the membranes of the Ovulum. But
as the foramina in these membranes invariably correspond both with each
other and with the apex of the nucleus, a test of the direction of the
future Embryo was consequently found nearly as universal, and more
obvious than that which I had previously employed.

To determine in what degree this account of the vegetable Ovulum differs
from those hitherto given, and in some measure, that its correctness may
be judged of, I shall proceed to state the various observations that have
been actually made, and the opinions that have been formed on the
subject, as briefly as I am able, taking them in chronological order.

In 1672, Grew* describes in the outer coat of the seeds of many
Leguminous plants a small foramen, placed opposite to the radicle of the
Embryo, which, he adds, is "not a hole casually made, or by the breaking
off of the stalk," but formed for purposes afterwards stated to be the
aeration of the Embryo, and facilitating the passage of its radicle in
germination. It appears that he did not consider this foramen in the
testa as always present, the functions which he ascribes to it being
performed in cases where it is not found, either, according to him, by
the hilum itself, or in hard fruits, by an aperture in the stone or
shell.

(*Footnote. Anatomy of Veget. begun page 3. Anatomy of Plants page 2.)

In another part of his work* he describes and figures, in the early state
of the Ovulum, two coats, of which the outer is the testa; the other, his
middle membrane, is evidently what I have termed nucleus, whose origin in
the Ovulum of the Apricot he has distinctly represented and described.

(*Footnote. Anatomy of Plants page 210 table 80.)

Malpighi, in 1675,* gives the same account of the early state of the
Ovulum; his secundinae externae being the testa, and his chorion the
nucleus. He has not, however, distinguished, though he appears to have
seen, the foramen of Grew, from the fenestra and fenestella, and these,
to which he assigns the same functions, are merely his terms for the
hilum.

(*Footnote. Anatome Plant. page 75 et 80.)

In 1694, Camerarius, in his admirable essay on the sexes of plants,*
proposes, as queries merely, various modes in which either the entire
grains of pollen, or their particles after bursting, may be supposed to
reach and act upon the unimpregnated