FI-M-TION.] IN CAMPANULACE.E. 221 



collecting hairs, nor even when they are drawn inwards by 

 the latter during their act of retraction. 



There is, therefore, no communication between them and 

 the interior of the style. 



As to the immediate cause of this retraction of the hairs, 

 without pretending to give a certain explanation of it, I think 

 it may be ascribed to the absorption of the liquid contained 

 both in the hair and in the cavity at its base, an absorption, 

 the effect of which will be to pull back the hair into the 

 cavity, at least I see no other part whose action can produce 

 the phenomenon. 



An examination of the structure of the external stratum 

 of the style and stigmatic arms, has already tended to show 

 the baseless character of the opinion held by those physiolo- 

 gists who think that fertilisation can take place by the action 

 of the pollen upon this part ; an opinion offered with doubt 

 by Cassini and Alphons.e De Candolle, asserted, on the con- 

 trary, in the most positive manner, by Treviranus, who, in 

 his Physiology, vol. ii. p. 343, considers the internal stigmatic 

 surface to be formed of papillae analogous to those which 

 sometimes terminate the petals, while, according to him, the 

 hairs covering the external surface of the style and stigma, 

 perform the part of the stigmata. Link (Philosophia Botanica, 

 2nd edition, vol. ii. p. 222), also admits that fertilisation takes 

 place by these hairs, whose points, he says, are destroyed 

 while the base remains, and so present a large opening which 

 leads into the style. 



We therefore see that the most distinguished botanists 

 entertain opinions either doubtful or contrary to the most 

 probable analogies. Nevertheless, in dissecting the true 

 stigma of Campanulas, that is to say, the inner face of the 

 stigmatic arms, after their divergence, we find that the grains 

 of pollen, scattered over the surface adhere to it, as to all true 

 stigmas, first by aid of the fluid that lubricates them, and 

 finally, by the production of pollen-tubes which penetrate it, 

 and soon mark a cord of long soft vesicular tissue, which 

 occupies the centre of the style. 



This cord of conducting tissue, of hexagonal form, in the 

 true Campanulas, whose stigma has three arms, is perfectly 



