. I. ACCESS OF THE POLLEN. f$f 



and gelatinous fluid exuding or exploding from the 

 globule ; still it will admit of being conducted 

 through the channel of the tubes of the style, al- 

 though no central canal should exist in it. 



But another question has also arisen out of the Quantity 

 subject with regard to the quantity of pollen neces- necessary, 

 sary to effect impregnation. Adanson was of opi- 

 nion that the smallest possible particle, if conveyed 

 to the ovary is sufficient. But this opinion is sup- 

 ported by no proof, and is even contradicted by later 

 observation ; the merit of having ascertained the 

 fact seems due to Koelreuter, whose experiments 

 are decisive of the question. The globules of 

 pollen contained in all the anthers of an individual 

 flower of Hibiscus syriacus, were 4803, of which 

 5O or 60 at least were necessary to effect a complete 

 impregnation. For when the attempt was made 

 with a smaller number the seeds were not all 

 ripened, though those that were ripened were per- 

 fect. Ten globules were the least by which the 

 impregnation even of a single seed could be effected 

 in this plant.* But in the Mirabilis Jalappa and 

 longiflora, the flowers of which contained about 

 30O globules of pollen, two or three were found 

 sufficient for impregnation, as the seed was not im- 

 proved by the application of more. It was also 

 found that the impregnation of flowers having two 

 or more styles was completely effected, even when 



* Willdenow, p. 323. 

 5 



