Botany.] 
NATURAL HISTORY. 
541 
and consequently of the base of the nucleus, the position of 
whose apex is therefore .readily determined. 
In this state of my knowledge the subject was taken up in 
1818, by my lamented friend the late Mr. Thomas Smith, 
who, eminently qualified for an investigation where minute 
accuracy and great experience in microscopical 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 corre- 
spond both with each other and with the apex of the nucleus, 
a test of the direction of the future Embryo was conse- 
quently found nearly as universal, and more obvious than 
that which I had previously employed. 
To determine in what degree this account of the vege- 
table Ovulum differs from those hitherto given, and in some 
measure, that its correctness may be judged of, I shall pro- 
ceed to state the various observations that have been ac- 
tually 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 oppo- 
site 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 germi- 
nation. 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. 
* Anatomy of Veget, begun p. 3. Anat, of Plants, p. 2. 
