allied to the Natural Order Burmanniaceae. 551 



parted petaloid perianthium. An aphyllous erect stem, with imperfectly de- 

 veloped leaves, is also a character not uncommon to many terrestrial Orchidece. 

 Besides this, several instances are now recorded of the full development of three 

 perfect stamens and three stigmata in orchideous plants. If these considera- 

 tions alone were held in view, omitting the very material one of the stamens 

 and stigmata, it would be difficult to draw a line of distinction between the 

 structure of these plants and that of Orchidece ; but the position of the sta- 

 mens, and other characters, sufficiently remove them apart. 



Another analogous fact is deserving of notice : on examining the stigma of 

 Dictyostega after flowering, it will be found to be crowded with bundles of 

 white cottony filaments, which may be seen even with a common lens to con- 

 sist of pollen-tubes issuing in a body from the cells of the anthers and pene- 

 trating the stigma, leaving their ends exserted, and clavately terminated by 

 their respective grains, thus displaying in a very beautiful manner the sin- 

 gular mode of fecundation so ably illustrated by Mr. Brown in his admirable 

 paper on that subject, published in the 16th volume of the Transactions of this 

 Society. The pollen also in its texture presents great resemblance to that of 

 the Orchidece, its component granules cohering in like manner into a solid 

 waxy mass previous to the dehiscence of the anthers. 



The position of the several parts of the flower in Dictyostega and the allied 

 genera will be seen to offer very peculiar characters, to an examination of 

 which I was led by the suggestions of Mr. Brown. This profound botanist 

 was, I think, the first who observed* that the pistilla, when distinct, or their 

 component parts, when united, are generally placed opposite to the petals in 

 Dicotyledones, while he believed the cells of the trilocular ovarium, or the 

 component parts of the unilocular ovarium with three parietal placentae in 

 Monocotyledones, to be situated uniformly opposite to the divisions of the outer 

 series of the perianthium ; and in his learned Memoir on Cyrtandracece, lately 

 published (" Plantse Javanicse," p. 110), he has given a very interesting de- 

 monstration of the structure of the ovarium, and the relation which placentae 

 and stigmata bear to the segments of the perianthium in several different 

 families. 



Mr. Brown considers that in Orchidece the stigmata alternate with the 

 * Appendix to Denham's Travels, p. 243. — 1826. 



