40 Mr. R. Brown on the relative position of 



in Orchidece each apparent stigma is formed by the conflu- 

 ence of the two stigmata of one and the same carpel, is proved 

 by tracing to their origins their vascular cords, which are 

 found to coalesce with those of the three outer fohola of the 

 perianthium. 



This view of the composition of the ovarium in Orchidece 

 is confirmed by finding that it agrees with the ordinary ar- 

 rangement in monocotyledonous plants ; namely, the op))Osi- 

 tion of the double parietal placenta to the three inner divi- 

 sions of perianthium *, while in Apostasia the three placentae 

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

 sions ; and it is further strengthened on considering what 

 takes place in Scitaminea, where the same agreement is found 

 botli in the placentae of the trilocular ovarium, which in this 

 family is the ordinary structure, and in the unilocular, which 

 is the exception. 



I am aware that the agreement of Orclddece with the usual 

 relation of parts in Monocotyledones is not admitted by M. 

 Achille Richard, nor by Mr. Lindley, who has adopted his hy- 

 pothesis respecting the structure of the flower in this family. 

 According to M. Richard, the outer series of perianthium is ge- 

 nerally wanting, being found only in one genus, Epistephium : 

 the three outer divisions actually existing in the whole order, 

 according to this view, become petals, and the three inner di- 

 visions sterile petaloid stamina. 



I have some years agof stated several objections to this 

 hypothesis ; at present I shall advert to one of those only, 

 considering it as conclusive ; namely, the position of the two 

 lateral stamina, which are generally rudimentary, but in some 

 cases perfectly developed, in this family. In several species 

 of Cypi'ipedium, which is one of these cases of perfect deve- 

 lopment, I had then ascertained, by means of numerous trans- 

 verse sections made at various heights in the column and at 

 its base, that their vascular cords united with those of the two 

 lateral inner divisions of the flower, while that of the third, 

 generally the only perfect stamen, is manifestly opposite to 

 the anterior division of the outer series. The position of sta- 

 mina, therefore, so far from being regular, as the hypothesis 

 in question considers it, is absolutely without example, two 

 of the inner series being opposite to two of the supposed outer 

 series of stamina. 



A very different view respecting the formation of the ova- 

 rium in Orchidea is that first advanced by Mr. Bauer and 



* Denliam, Trav. in Afr. Append, p. 243. 

 t Linn. ISoc. Trans, vol. xvi. p. 698. 



