220 On the Penetration of the Cuticle into the Stomata. 



likewise with their appendages situated in the interior of the leaf. 

 It is true they sink into the furrows proceeding between the adja- 

 cent cells, and are frequently provided at these places with pro- 

 jecting bands immersed in the farrows ; but a composition of 

 originally distinct pieces is in so far incapable of being detected, as 

 it is impossible to separate them into the individual pieces cor- 

 responding to these divisions by the application of acids. This 

 circumstance will naturally be considered by those phytotomists 

 who, with Treviranus, Schleiden and Payen, look upon the cuticle 

 as a part distinct from the epidermatous cells, as a hardened se- 

 cretion, to support their view ; but in reference to this point, it 

 is in my opinion requisite to take the greatest precaution not to 

 be led to a rash conclusion. 



I have already in my memoir on the cuticle, ' Linnsea,' vol. xvi., 

 not by any means denied that important reasons appear to speak 

 in favour of this view, and I am at present just as far from wishing 

 to deny the possibility that this view is correct and the one sup- 

 ported by me erroneous; but nevertheless I still believe, that the 

 view according to which the cuticle is formed of the outer layers 

 of the epidermatous cells themselves is far more probable. If 

 the cuticle owed its origin to a secretion taking place at the sur- 

 face of the epidermis, it ought to be possible to find the primary 

 membrane of the epidermatous cells beneath it, and observe it 

 pass into the lateral walls of these cells. I have not succeeded 

 in doing this, but, on the contrary, I believe I have traced in 

 many cases the primary membrane of the lateral walls of the 

 epidermatous cells through the cuticle to the surface of the 

 latter, and I thence concluded that the cuticle was not a 

 peculiar membrane distinct from the epidermis, but owed its 

 peculiarities to a metamorphosis of the substance of the outer 

 layers of the epidermatous cells themselves. Undoubted ana- 

 logies may be adduced in support of such metamorphoses of in- 

 dividual parts of the cell-wall (or according to the views of Payen, 

 in favour of a deposition of organic substances in the cellulose 

 of the original cell-wall, whence this acquires different proper- 

 ties). I would especially call to mind, in this respect, the nature 

 of the primary membrane of the prosenchymatous cells of most 

 woods, which membrane originally exhibited all the characters of 

 pure cellulose, while in the developed wood it presents the same 

 property as the cuticle, of being coloured yellow by iodine and 

 of resisting the action of sulphuric acid. I would moreover call 

 to mind the brown-coloured parenchymatous cells which inclose 

 the vascular bundles of ferns, and in which, in some cases, not 

 all the walls, but only that directed towards the vascular bundle 

 and a portion of the lateral wall, undergoes that metamorphosis 

 into a thickened brown substance resisting the action of sulphuric 



