501 ON THE ORGANS AND MODE OF FECUNDATION 



have effectually concealed their true nature ; and accord- 

 ingly they have uniformly been considered as forming 

 parts or appendages of the labellum, with which indeed 

 their bases cohere. That they are really stigmata, how- 

 ever, I have proved by a careful examination of the tissue 

 of their secreting surface, by the action of the pollen arti- 

 ficially applied to this tissue, by the descent of its tu]:)es, 

 hereafter to be described, along the upper surface of the 

 styles which is destitute of epidermis, and by the conse- 

 quent enlargement of the ovarium. Di/domeris of Mr. 

 Don,^ which may also be regarded as a species of Habe- 

 naria, is another example of nearly the same kind ; and the 

 702] description of stigma which, in 1813, I introduced into 

 the character of Sat^riuiu,^ implies an analogous develop- 

 ment in that genus. 



On the relative position of stamina and stigmata in the 

 column of an Orchideous plant, it may be remarked that 

 there is hardly an instance of a perfectly developed stamen 

 and stigma placed opposite to each other, and consequently 

 deriving their vessels from the same cord. 



Tor, in the ordinary structure of the family in which 

 only one perfect stamen is produced, the corresponding 

 stigma loses entirely or in great part its proper function, 

 which it recovers, so to speak, in those cases where this 

 stamen becomes imperfect, or is destitute of an anthera : 

 and hence, perhaps, it may be said that to obtain in any 

 case the complete devolopment of the lateral stamina, and, 

 what is of greater importance, to ensure in all cases the 

 perfection of the lateral stigmata, these organs are never 

 placed opposite, but uniformly alternate with each other. 



The general conformation of the ovarium, v/ith regard to 

 the number and relative position of the parietal placentae, 

 and the arrangement of their numerous ovula, has long 

 been well understood. But the early structure and evo- 

 lution of the unimpregnated ovulum have not yet, as far as 

 I know, been in any degree attended to. 



In its gradual development, the ovulum exhibits a series 



' Frodr. Flor. Nepal, p. 26. 



- Ait. Hort. Keto. ed. 2, vol. v, p. 196. 



