494 ON THE ORGANS AND MODE OF FECUNDATION 



family. But I have since on several occasions more ex- 

 plicitly stated that opinion, which, until lately, I always 

 considered the most probable hypothesis on the subject. 

 At tlie same time its probability in this family appeared to 

 me somewhat less than in Asclepiadeee. Tor in Orchideae 

 a secreting surface in the female organ, apparently destined 

 to act on the pollen without the intervention of any other 

 part, is manifest ; and some direct evidence of the fact 

 existed, though not then considered satisfactory. In Ascle- 

 piadeas, however, I entertained hardly any doubt on the 

 subject ; the only apparently secreting surface of the stigma 

 in that family being occupied by the supposed conductors 

 of the male influence, and no evidence whatever, with which 

 I was acquainted, existing of its action through any other 

 channel. 



In 1810 or 1818 I received from the late celebrated 

 Aubert du Petit Thouars some printed sheets of an in- 

 tended work on Orchideae, which, with a few alterations, 

 was completed and published in 18 2. "2.^ 



From the unfinished work, as well as that which was 

 afterwards published, it appears that this ingenious ])ota- 

 nist considered the glutinous substance connectins; the 

 grains or lobules of pollen as the " aura seminalis" or fe- 

 cundating matter ; that the elastic pedicel of the pollen 

 mass, existing in part of the family, but according to him 

 not formed before expansion, consists of this gluten ; and 

 that in the expanded flower the gluten which has escaped 

 from the pollen is, in all cases, in communication with the 

 stigma. 



He describes the stigma as forming on the surface of 

 coil the column a glutinous disk, from which a central thread 

 or cord of the same nature is continued through tlie style 

 to the cavity of the ovarium, where it divides into three 

 branches, and that each of these is again subdivided into 

 two. The six branches thus formed, are closely applied to 

 the parietes of the ovarium, run down on each side of the 

 corresponding placenta to its base, each giving oft' nume- 



' Hist, des Orchid, p. 14. 



