ON ORCHIDKE AND ASCLEPIADE^. 551 



But as such granules, at the period of iiisertiou, are either 

 very few in number, or apparently altogether wanting, I 

 am still inclined to consider them rather as furnishing the 

 nourishment of the Tube than as being the essential 

 agents in fecundation ; the really active particles in this 

 function being probably much more minute. 



These supplementary observations may be concluded 

 with the remark, that although the descent of Tubes 

 derived from the Pollen into the cavity of the Ovarium, 

 and their insertion into that point of the Ovulum where the 

 Radicle of the future Embryo is seated, has been abso- 

 lutely ascertained in several species of Orchideae and in one 

 of Asclepiadeae, and probably will be found in the whole of 

 these two extensive families, yet it does not follow that 

 this descent and insertion of Tubes should be expected to 

 extend to all Phsenogamous plants ; for among these some 

 structures of the female organ exist, which hardly admit of 

 this oeconomv. 



LoNTinx; Jnlt/msl, 183S. 



