PHANEROGAMIA : FLOWERS. 377 



few parallel vascular bundles. The stigma, on the other hand, 

 corresponds to the lamina, and is so imperfectly developed that in 

 most instances it contains no vascular bundles. In a few cases 

 interesting modifications of cellular tissue are presented in the in- 

 terior of the germen ; yet oil-passages ( Umbelliferce), milk-vessels, 

 and cells containing crystals, &c., occur here and there. The exter- 

 nal epithelium of the outer surface is commonly soon changed into 

 epidermis, which often exhibits stomates, and under this the paren- 

 chyma is somewhat lax and almost spongy. The surface of the 

 germen exhibits all the various appendages of young epidermis, 

 hairs, prickles, glands, &c. The style is sometimes clothed with 

 hairs, which are termed collecting hairs (pili collector es\ because 

 the pollen remains attached to them. The peculiar hairs upon the 

 styles of some of the Campanulacea are worthy of attention ; they 

 have already been spoken of (29.). They have served as the 

 basis for many fanciful notions. The formation of the epithe- 

 lium of the inner surface is more important ; it is sometimes deve- 

 loped with the next subsequent layers into a true epidermis, 

 but only in the cavity of the germen (rarely, as in Passiflora and 

 some Cruciferce, furnished with stomata). On the stigma it is 

 converted, either partially or entirely, into papillae, as it also is 

 sometimes in the canal of the style, if this is distinctly hollow , 

 and in the cavity of the germen along the spermophores, as far as 

 the seed-buds, where the papillae frequently become long hairs. 

 All these papillae commonly secrete at the time of the perfecting of 

 the pistils an adhesive substance, containing gum or sugar, the stig- 

 matic fluid. A similar substance is frequently secreted in the 

 intercellular spaces of the cellular layers lying immediately beneath 

 the epithelium of the stigma and the styles, and often so copiously 

 that the cells are loosened from their union with one another, and 

 lie loosely imbedded in this mucilaginous, semi-fluid matter. The 

 process may be easily followed in the Orchidacece and the Onagracece. 

 The epithelium generally, so soon as it becomes papillose, together 

 with all the cellular tissue and the secreted matter, is termed con- 

 ducting cellular tissue (tela conductrix, conductor fructificationis, Hor- 

 kel; tissu conducteur, Brongniart). In rare cases, in the Asclepiada- 

 cecB and Apocynacece, where the upper opening of the canal of the 

 style is perfectly closed, a conducting cellular tissue of this kind is 

 formed through the thickness of the wall to the outer surface. In 

 the Asclepiadacece a peculiar secretion is presented at the five angles 

 of the great body formed by the blending of the stigmas, from which 

 proceed five glandular, scarcely organised structures, each with 

 two arms, coated with viscine, and, as has already been noticed, 

 receive the pollen masses at the time of the dehiscence of the an- 

 thers. 



Of the last-mentioned matters, the structure of the conducting cellular 

 tissue only is of essential importance. But this again gives striking evi- 

 dence of how vague and obscure all investigations and so-called theories 

 remain, when they are not based on the history of development. Brong- 



