IN ORCHIDE^ AND ASCLEPIADE^. 503 



that dehiscence which, though very remarkable in this order, 

 is in a great degree analogous to that taking place in most 

 Cruciferse, in several Leguminosse, and in other families of 

 plants. It may also be objected to Mr, Bauer's view of 

 the composition of ovarium, that the arrangement of the 

 parietal placentae, which on this hypothesis would occupy 

 the axes of the three alternate component parts, is contrary 

 to every analogy ; while the position of the stigmata, if my 

 account should prove to be correct, aifords evidence nearly- 

 conclusive of the ovarium being formed of only three parts. 



In those genera of Orchidese in which the lateral stamina 

 are perfect, and the middle stamen without anthera, namely, 

 Cypripedium and Apostasia, all these lobes or divisions of 

 stigma are equally developed, are of nearly similar form 

 and texture, and, as I have proved by direct experiment in 

 Cypripedium, are all equally capable of performing the 

 proper function of the organ. 



In most other cases the anterior lobe, or that placed poi 

 opposite to the perfect stamen, and deriving its vessels from 

 the same cord, manifestly differs both in form and texture 

 from the other two. To this anterior, or upper lobe, as it 

 generally becomes in the expanded flower, the glands always 

 belong to which the pollen masses become attached, but 

 from which they are in all cases originally distinct, as may 

 be proved even in Ophrydese. 



According to my view, therefore, of the mode of impreg- 

 nation, its office is essentially different from that of the 

 two lateral lobes or stigmata, which in various degrees of 

 development are always present, and in all cases, when the 

 ovarium is perfect, are capable of performing their proper 

 function. 



The greatest development of these lateral stigmata takes 

 place in the tribe of Satyrinse or Ophrydese, as in many 

 species of Habenaria, those especially which are found 

 near or within the tropics ; and still more remarkably in 

 Bonatea speciosa, a plant hardly indeed distinguishable 

 from the same extensive genus. 



It would seem that in Bonatea the extraordinary develop- 

 ment and complete separation of these lateral stigmata, 



