56 



in retracting thus within itself, draws with it a few grains 

 of pollen, which thus appear to penetrate the tissue of the 

 style, but which in fact are always on the outside of the hair. 

 With care these hairs may be pulled out again by the point 

 of a needle, and then the pollen-grains which appear to have 

 penetrated the style are immediately expelled. Such pollen- 

 grains undergo no change during their application to the 

 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 phe- 

 nomenon. 



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 fertilization can take place by the action 

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

 by Cassini, and Alphonse DeCandolle, admitted 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 papillse 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, 

 ijnd edition, vol. ii. p. 22^), also admits that fertilization 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 stig- 

 ma of Campanulas, that is to say, the inner face of the stig- 

 matic 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, 



