112 ORGANS AND FUNCTIONS OF PLANTS. 



Process of the pollen penetrating into the pistil. a, a grain of 

 pollen from the swallow- wort with its tube and granules ; b, 6, 

 seed-organs of the same plant with the pollen tubes penetrating 

 to them ; c, pollen of snapdragon with its tubes penetrating into 

 d, the pistil ; e, triangular grain of pollen in the tree primrose ; 

 /, /, its tubes; g, the tissue of the pistil. 



M. Adolphe Brongniart, on the other hand, says 

 there are no vessels for such conveyance, but the 

 granules pass into the spaces between the cells in the 

 summit ; and he observed them penetrate deeper and 

 deeper till they reached the seed organ, where they 

 actually find their way into the interior of the nascent 

 seeds by means of a delicate membranous tube, at the 

 end of which is a minute vesicle in which the embryo 

 plant is formed, the neck of the vesicle forming the 

 radicle. 



M. Balliard is said to have traced coloured liquids, 

 sucked up by the spongelets of the summit along the 



