952 



der which the author includes those cases in which the style, the 

 stigma, or the absorbent hairs of the stigma act as organs of ingestion 

 in the process of fertilization. First, of fertilization by means of the 

 style, especially by means of the curious hairs of the style in Campa- 

 nula. The author saw pollen-globules or grains in the hairs of the 

 style, sometimes in remarkable abundance. He regards it as decided 

 that fertilization takes place by means of these hairs ; even the re- 

 traction (Einsliilpung) of these hairs could only serve to approximate 

 the pollen to the elongated cells of the central bundle of spiral ves- 

 sels. Although, after the separation of the lobes of the stigma (Nar- 

 benarme) pollen reaches the inner side of the lobes which are cover- 

 ed with hairs, and polleu-tubes become there developed, yet fertiliza- 

 tion cannot take place by this means, since that condition is but 

 seldom observed. Moreover, the author coated the stigma with a 

 solution of gum, previous to the separation of the lobes from each 

 other, and yet fertilization took place. 



" To impregnation of the stigma the author refers all cases in 

 which the formation of tubes from pollen-grains upon a naked stig- 

 ma, that is, one destitute of hairs, cannot be shown to occur, as in 

 Petunia, Nicotiana, Alropa, &c. The pollen here falls on a mucous 

 covering, which mucus is produced by peculiarly formed mucus-cells. 



" Impregnation of the absorbent hairs of the stigma, or of the pa- 

 pillae upon it, takes place in many plants, as for instance, in Matthi- 

 ola annua, and others. The papillae consist of three membranes : 

 the middle one is termed by the author the raucous membrane ; it is 

 covered with a delicate external membrane, and incloses an internal 

 tube, whose granular contents are coloured brown by iodine. We 

 must here distinguish the impregnation which takes place by pene- 

 tration of the tubes into the middle membrane of the hair, since the 

 cuticle is in that case wanting, as the author has shown with regard 

 to Matthiola annua, in the third part of his Elements. Further, im- 

 pregnation of the absorbent hairs by penetration of the tubes into 

 their cuticle, as in Glaucium violaceura ; impregnation of the absorb- 

 ent hairs by absorption, particularly in Capsella Bursa-pastoris, a 

 very frequent occurrence ; impregnation of the absorbent hairs by 

 contact, as in Clarkia pulchella. In all these cases a formation of 

 tubes takes place. Frequently, and especially in those flowers which 

 have the stigma covered with large masses of pollen, we see that only 

 those granules succeed in forming tubes which are restrained by the 

 deeper situated pollen-layers from coming in contact with the surface 

 of the stigma or with the hairs ; whilst those granules, which are in 



