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 pai'ts, and therefore confirming the accu- 

 racy of the theory of Kunth. 



Other opinions, more or less resembling these, have been formed 

 by other pei'sons, 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 jneces ; 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 hack '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 sjnir, 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 pai'ts 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 wall 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. 



