Cuticle into the Stomata. 219 



the intercellular passages on tlic inferior surface of the epidermis 

 to neighbouring funnels, and form in this manner connexions 

 with one another ; for instance^, on the under side of the leaves of 

 Helleborus niger and viridis, and in the leaves of Euphorbia Caput 

 Medusa. Lastly, it occurs in some plants, for instance, in the leaves 

 of Betula alba and Asphodelus luteus, that such appendages pene- 

 trate into all the intercellular passages situate beneath the epider- 

 mis, and extend in the form of a reticulate membrane over the 

 whole under surface of the epidermis, so that the epidermatous cells 

 are clothed on both sides by a true cuticle, in which the inner 

 cuticle does not, it is true, form a continuous membrane, not pass- 

 ing in between the epidermatous cells and the parenchymatous 

 cells adherent to them, but exhibiting at the place of connexion of 

 every parenchymatous cell with a cell of the epidermis, a void 

 corresponding to the size of the place of connexion. A similar 

 inner perforated cuticle may likewise occur without the epidermis 

 being interrupted by stomata; but this is rare, at least I have 

 hitherto found it only in the epidermatous cells of the upper 

 surface of the leaf of Helleborus niger and viridis. 



When the epidermis consists of several superposed layers of 

 cells, as in Cereus peimvianus and Cactus Opuntia, the continuation 

 of the cuticle clothes the lateral walls of the portion of the spi- 

 racle situated in this thickened epidermis ; it consequently ap- 

 pears not merely in the form of a wide expanded funnel, but 

 rather in that of a tube, and then constitutes the organ described 

 and figured by Gasparrini under the name of cistoma. In this 

 case the tube-like continuation of the cuticle likewise terminates 

 with an open embouchure at the inferior limit of the epidermis ; 

 although it sometimes appeared to me to continue for a short 

 distance into the portion of the spiracle situated between the 

 green parenchymatous cells ; for instance, in Cereus peruvianus 

 and likewise in Protea mellifera, whose leaves, moreover, possess 

 a simple epidermis. 



This continuation of the cuticle penetrating into the interior 

 of the organs, is acted upon, as already observed by Payen, by 

 iodine and sulphuric acid precisely like the cuticle situated on 

 the outer side of the epidermis. A composition of fibres, which 

 is ascribed to it by Gasparrini, can no more be demonstrated in 

 it than in any other vegetable membrane ; but just in like man- 

 ner as fibre-like thickened bands occur on the cuticle of many 

 plants, so do we find the same circumstance in some of the plants 

 I have examined ; for instance, Cereus peruvianus and Helleborus 

 niger, and likewise on the funnel-shaped membrane clothing the 

 outer side of the spiracles. As, moreover, the cuticle of most plants 

 does not admit of our distinguishing any composition of individual 

 pieces correspondent to the subjacent epidermatous cells, so is it 



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