discovered the fifth or missing petal to be present occasionally in the 
garden Balsam, and always in Hydrocera triflora; both these Bota- 
nists finding in the genus Hydrocera the back piece, which is simple in 
Impatiens, composed of two parts, and therefore confirming the accu- 
racy of the theory of Kunth. 
Other opinions, more or less resembling these, have been formed 
by other persons, for which I have no room in this place; and they 
are the less important because I think the plant now before us shows 
that Kunth’s theory is the only one that is correct. 
If we make a section horizontally through a young flower-bud of 
this plant, we find the appearances represented at fig. 1. in the accom- 
panying plate. There is in the centre an ovary of five cells; with 
these alternate the five stamens, of which the fifth or anterior has a 
longer filament than the others; so far the structure is regular, and we 
have all the necessary evidence of the flower, however irregular, being 
formed upon a quinary type. Right and left of the stamens stand the 
two innermost pieces ; these cannot be simple, because they are. oppo- 
site the intermediate stamens ; but their two-lobed figure, when full 
grown, shews that each is double, and then, their apparent centre 
being in fact their united margins, they alternate with the anterior 
stamens, and so fall into the place usually destined for petals. The 
last mentioned parts are half enveloped by the back piece, which 
might, from its position, be the fifth petal; but the case of Hydrocera 
shewing it really to consist of two united parts, they must be opposite 
the stamens, and consequently are sepals. Next comes the spur, which 
overlaps the back piece, and stands opposite the anterior stamen ; as 
no tendency to divide on the part of this piece is ever found it must 
be a sepal. Finally, the external scales, placed right and left of the 
whole flower, alternate with those parts already shewn to be sepals, 
and consequently are recognized as the two parts of the calyx required 
to complete the quinary place of the whole flower. It will be re- 
marked, that a fifth petal has not been found; if the eye is turned upon 
the back piece, already found to be composed of two sepals, it will be 
seen that a part is missing between those two and the two corres- 
ponding stamens; and this is the place where the abortion of a fifth 
of the corolla may, upon the evidence of this flower, be assumed to 
_ occur, and where it is proved to take place by the evidence of Hydro- 
cera, in which the part missing in the Balsam makes its appearance. 
The annexed diagram will 
serve to illustrate the preceding 
observations, the parts of the 
flower, as they really exist in 
Impatiens being projected upon 
a plane consisting of five circles, 
of which the exterior (S) repre- 
sents the sepals or calyx, the 
next (P) the petals or corolla, 
the third (s) the stamens, the 
fourth (c) the carpels, and the 
central (p) the placenta, or axis. 
With regard to the remain- 
der of the analyses, Fig. 2. re- 
presents the stamens; 3. the 
ovary, style, and stigma; 4. the 
ripe fruit, 
