OP CENTRAL AFRICA. 293 



relations in the reduced series of pistilla should have sug- 

 gested the opinion, that in a complete flower, whose [337 

 parts are definite, the number of stamina and also of pistilla 

 is equal to that of the divisions of the calyx and corolla 

 united in Dicotyledones, and of both series of the perian- 

 thium in Monocotyledones. 



This assumed complete number of stamina is actually 

 the prevailing number in Monocotyledones ; and though in 

 Dicotyledones less frequent than what may be termed the 

 symmetrical number, or that in which all the series are 

 equal, is still found in decandrous and octandrous genera, 

 and in the greater part of Leguminosae. The tendency to the 

 production of the complete number, where the symmetrical 

 really exists, is manifested in genera belonging or related 

 to those pentandrous families in which the stamina are 

 opposite to the divisions of the corolla, as by Samolus 

 related to Primulacese, and by Bseobotrys, having an analo- 

 gous relation to Myrsinese ; for in both these genera, five 

 additional imperfect stamina are found alternating with the 

 fertile, and consequently occupying the place of the only 

 stamina existing in most pentandrous families. Indications 

 of this number may also be said to exist in the divisions of 

 the hypogynous disk of many pentandrous orders. 



With respect to the Pistilla, the complete number is 

 equally rare in both the primary divisions of phsenogamous 

 plants. In Monocotyledones the symmetrical number is 

 very general, while it is much less frequent in Dicotyledones, 

 in which there is commonly a still further reduction. 



Where the number of Pistilla in Dicotyledones is reduced 

 to two, in a flower in which both calyx and corolla are 

 present and their division quinary, one of these pistilla is 

 placed within a division of the calyx, the other opposite to 

 a petal or segment of the corolla. In other words, the 

 addition to the solitary pistillum, (which is constantly an- 

 terior or exterior), is posterior or interior. This is the 

 general position of the component parts of a bilocular 

 ovarium, or an ovarium having two parietal placentae ; 

 and in flowers whose division is quinary, I can recollect no 

 other exceptions to it than in some genera of Dilleniacese. 



