74 Dr. Schleiden on Cellular Membrane in Mosses. 



velopment we shall always obtain a valid ground for admitting 

 the identity of the elements, and thence we shall also be jus- 

 tified in assigning other occurrences in the life of the cell of 

 plants by analogy to those cells in which they have not yet 

 been expressly observed. 



So far as I am aware, up to the present time the occurrence 

 of a spiral for] nation has been ascertained in the reproductive 

 organs of Ilepatlcai only in the elaters and fruit valves*. But 

 these are not less strikingly developed in the vegetative or- 

 gans of Marchantiaceae. The parenchyma of the leaf in Mar- 

 chantia jiolymorpha and Fegatella conica consists almost en- 

 tirely of cells, the partitions of which appear most distinctly 

 porous or (especially in M. polymorphs.) thickened beau- 

 tifully with network. This thickening of the cell partitions 

 takes place to so great a degree in the older parts and in the 

 proximity of the midrib, that by transverse sections the pore- 

 channels may be plainly recognised. 



Amongst mosses, the true Dicrana, for example D. Schra- 

 deri, spurium, &c. are distinguished by leaf-cells, of which 

 the sides are very thick and the partitions evidently pierced 

 through, frequently by very wide, frequently by funnel-shaped 

 pore-channels, just as is apparent in the epidermis of so many 

 phanerogamous plants. And still more conspicuously do these 

 spiral and porous formations display themselves in Sphagnea, 

 and in the nearly related group of Leucophanece established 

 by Hampe. The structure of the cells of Sphagnum, Leuco- 

 bryum vulgare, Hampe, (Dicranum glaucum) and Octoblepha- 

 rum albidum, seems to me to have been sufficiently discussed 

 by Mohl ; here therefore I can only add some inconsiderable 

 contributions. Those peculiar and large pores which in the 

 older state of the leaf become real holes (just as in the parti- 

 tions which separate the vessels of phanerogamous plants), 

 besides being found in the species above-mentioned, also oc- 

 cur in Octoblepharum cylindricum, Schimp. Didymodon sphag- 

 noides, Hook., and in Leucobryum minus, albidum, and longi- 

 folium, Hampe f. All the mosses reckoned amongst Leuco- 



* Beautiful and interesting forms are especially met with here in Pellia 

 epipliylla. 



f The determination of these mosses is to be depended on, as they were 

 all communicated to me, with his accustomed kindness, by Hampe himself. 



