160 PROF. HENFREY ON THE 



ix. p. 112), from the consideration of tlie structure of the genus 

 Hydrocera. Through the kindness of Dr. Hooker, I have seen 

 further observations by himself and Dr. Thomson, which not only 

 confirm Eoeper's view, in reference to Hyd/rocera, but illustrate it 

 further by certain East Indian species of Imjpatiens, in which the 

 number of sepals is either regularly or occasionally the same as in 

 Hydrocera. In this genus the calyx has five sepals: first, the 

 posterior spurred sepal; next, two lateral sepals, corresponding 

 to the two small and usually green sepals oi Impatiens Balsamina ; 

 with two anterior sepals, which are mostly suppressed in Impa- 

 tiens. Within this circle occurs a whorl of five petals, the anterior 

 one being the so-called " double sepal" of Kunth, which is inside 

 the two anterior sepals just referred to. 



Payer (Traite d' Organogenic vegetale) states that he finds the 

 rudiments of this pair of anterior sepals on very young buds of 

 Imjpatiens Royleana. I have not been able to find them in the 

 Garden Balsam, nor in a developed state in the numerous mon- 

 strous specimens which I have examined. On the other hand, 

 the monstrosity presently to be described favours the doctrine of 

 Hoeper far more than that of Kunth. In order to explain it more 

 clearly, I have appended diagrams of the normal structure of 

 Impatiens and Hydrocera (figs. 1 and 2). 



It is a well-known fact that the common Double Balsams of our 

 gardens produce seed freely. Since only one circle of stamens 

 exists, we should scarcely have expected this ; but the fact is that 

 an extra coroUine whorl is produced without the suppression of 

 the stamens, and the metamorphosis takes place in a manner 

 which bears an interesting relation to certain general questions of 

 morphology, as well as to the theory of the flower of Impatiens. 

 In the common Double Balsams of our gardens the flowers usually 

 present a natural calyx, the small lateral sepals being often more 

 or less coloured, and sometimes gibbous or slightly spurred ; I 

 have never found the two anterior (suppressed) sepals developed. 

 Within the calyx stand five petals (a broad anterior one and two 

 pairs of lateral petals), which are, as usual, mostly more or less 

 adherent by their limbs on each side, but with their claws free. 

 Succeeding these are found five free petals resembling in appear- 

 ance the lateral petals of the previous whorl, standing in the usual 

 place of the stamens — that is, alternating with the normal petals, 

 as shown in the diagram (fig. 3). Next comes a circle of five 

 stamens, mostly all perfect, alternating with the preceding circle, 

 and therefore in the ordinary place of the carpels. Lastly, the 



