140 GENERATION. 



(comprising the papillae of the stigma) secretes a 

 mucilaginous fluid, which is more or less perceptible 

 upon its surface, and in the inter- cellular spaces. 



/. The pollen, dispersed by the dehiscence of the 

 anther, falls upon the stigma, and the essential mem- 

 brane of the pollen elongates itself as a tube, which 

 following the conducting tissue, extends itself to the 

 placenta and ovule. 



g. Arrived at the ovule, the pollen-tube enters the 

 aperture of its integuments, traverses the summit of the 

 nucleus (Mamelon d'impregnation Brong.), following 

 the inter- cellular meati, and attains the sac of the 

 embryo. 



h. The pollen-tube pushes the membrane of the sac 

 before it, folding it inside and around itself, causing its 

 own extremity to penetrate in appearance the sac of 

 the embryo. 



243. The extremity of the pollen-tube, having thus 

 attained the sac of the embryo, swells into a spherical 

 or ovoid form, and its contents change into cellular 

 tissue. It produces the lateral organs, one or two coty- 

 ledons ; but the original extremity, forming the plumula, 

 remains more or less distinct. 



L The part of the pollen-tube, situated above the 

 embryo, and which is strangled by this duplicature of 

 the embryo sac, which surrounds it, is obliterated sooner 

 or later, so that the embryo is effectively contained in 

 the embryo sac. 



k. In consequence of their development, the other 

 parts of the ovule give birth to the integuments of the 

 grain, and to the albumen ; but we cannot determine, 

 in a general manner, to which of the young organs of 

 the ovule the several parts of the seed are related. 

 This determination must result for each family, by a 

 study of its special mode of development. 



/. From these facts it results, that we have named the 

 sexes in plants quite wrong, for the grain of pollen must 

 be looked upon as giving the germ of the new being ; and, 

 therefore, the anther is a female organ, and the sac of the 



