FUNCTION.] COLLECTORS IN BELLWORTS. 



the pollen is developed, a little before the maturity of the 

 latter, while, by a dislocation of those cells, the pollen loses 

 all organic connexion with the lining of the anther; and 

 that, on the other hand, these cells are dried up, lacerated, 

 and disorganised, at the time when the pollen has acquired 

 its full development. 



In some plants, especially in Bellworts (Campanulacea3), a 

 provision is found for brushing the pollen out of the anthers 

 and conveying it to the stigma ; concerning which we have 

 the following observations by M. Adolphe Brongniart : 



" It has long been known that the external surface of the 

 upper part of the style, and of the stigmatic arms of Cam- 

 panulaceous plants, is covered with long hairs, which are very 

 visible in the bud, before the dispersion of the pollen, and 

 which are regularly arranged in longitudinal lines in direct 

 relation to the number and position of the anthers. 



" These hairs and their connexion with the pollen, at first 

 remarked by Conrad Sprengel in several species of Campa- 

 nula, and afterwards by Cassini, with more care, in Cam- 

 panula rotundifolia, have been observed by M. Alphonse De 

 Candolle in the whole Campanulaceous order, with the excep- 

 tion of the small genus Petromarula. At the period of dehis- 

 cence of the anthers, before the expansion of the corolla, and 

 when the arms of the style are still pressed against each other 

 in the form of a cylinder, these hairs cover themselves with a 

 considerable quantity of pollen, which they brush, so to speak, 

 out of the cells of the anther ; and for this reason they have 

 been named, like the analogous hairs in Composite, Col- 

 lectors. 



" At the period when the flower expands, the arms of the 

 style, or stigmata separate, and curve backwards, and the 

 anthers that surround them retire and shrivel up, after having 

 lost all their pollen ; but at the same time the pollen, which 

 was deposited on the outside of the style, detaches itself, and 

 the hairs that covered the surface disappear. 



" This led Cassini to call these hairs deciduous, and to say 

 that they disappear at the same time with the pollen which 

 they retained. There then remains, he says, upon the style, 

 nothing more than little asperities," 



