552 Mr. MiERS on some new Brazilian Plants 



placenta;, a relation most usual in cases of compound unilocular ovaria where 

 the number of stigmata and placentae is equal ; and that such is really its 

 relation appears to him to be proved by tracing to their origin their vascular 

 cords, which are found to coalesce with those of the three outer foliola of the 

 perianthium. This view of the composition of the ovarium in Orchidece, he 

 observes, is confirmed by finding that it agrees with the ordinary arrangement 

 of Monocotyledonous plants, viz. the opposition of the double parietal pla-' 

 centse to the three inner divisions of the perianthium, while in Apostasia the 

 three placentae of the trilocular ovarium are opposite to the three outer divi- 

 sions. The same agreement, he further observes, is found in Scitaminece, both 

 in the placentae of the trilocular ovarium, which in this family is its ordinary 

 structure, and in the unilocular, which is the exception. My observations 

 upon the structure of Burmanniacece afford to that order a different arrange- 

 ment as regards the position of stigmata. Dr. Von Martius, in illustrating 

 the genus Burmannia, has given a figure of the pistillum of B. hicolor, in 

 which the stigmata are placed opposite to the wings, and therefore alternate 

 with the inner segments of the perianthium ; but this probably may have been 

 an error of the draughtsman, since no such position is alluded to in the text. 

 I have in several instances opened with the utmost care the flowers of Bur- 

 mannia, and have found the stigmata manifestly placed as I have constantly 

 observed them in Dictyostega and the allied genera with unilocular capsules, 

 viz. opposite to the stamens, and to the inner segments of the perianthium, with 

 which the placentae also correspond, all being alternate with the outer seg- 

 ments: in Burmannia, however, owing to the complete inflection of the car- 

 pellary leaves to form the trilocular ovarium, the placentae thus extended 

 to the axis will be seen directed towards the middle of the cells, and opposite 

 to the outer segments of the perianthium, at the same time that all other parts 

 I'emain as before mentioned, in a similar position to that existing in Dic- 

 tyostega. 



This deviation from the usual order of relation may probably be accounted 

 for by the very ingenious views of Mr. Brown relative to the original compo- 

 sition of stigma, founded on the supposition that each simple pistillum or 

 carpel has necessarily two stigmata, which are to be regarded not as terminal, 

 but lateral, in the same manner that the placentae of each carpellary leaf are 



