37 



number of the Archiv, which, however, appeared only this 

 year, demonstrated that most of these observations were in 

 some respects erroneous, in others incomplete. He observed 

 that the cavities were not open, but closed by a membrane 

 somewhat above their centre ; he further saw that the cells 

 of the epidermis, contiguous to the cavities, were peculiarly 

 arranged; and lastly, that the cellular parietes adjacent to the 

 cavities had a reticulate porous appearance which is repre- 

 sented in his drawings. 



M. Schleiden connects these formations with the cavities 

 which originate in various plants by the falling off of the hairs, 

 with which the leaves are so frequently clothed in the bud. 

 He says that I had long since found quite similar formations 

 on the under surface of the leaves of Nymphcea odorata, but 

 the history of their development had been followed by him in 

 1833. M. Schleiden found that the leaves of Nuphar luteum, 

 so long as they remain in the bud, are clothed with long silky 

 hairs which subsequently fall off, and then exhibit open cavi- 

 ties, which have the appearance of round scattered cells. I 

 have at this moment no leaves of that plant at hand, but un- 

 fortunately this explanation of Dr. Schleiden is not applicable 

 to the leaves of the Nymphceae examined by me, as N. odorata, 

 ccerulea, alba (also the small variety). The round cells on the 

 under surface of the leaf of these Nymphaece may be observed in 

 the buds, and their outer side, somewhat vaulted, projects 

 above the surface of the epidermis ; a similarly formed cell is 

 situated immediately below each of these round tabular cells, 

 and both together have in general the same longitudinal dia- 

 meter as the adjacent cells of the epidermis. I compare these 

 round cells on the leaves of the Nymphcea with those similar 

 cells observed by me on the leaves of Zea Mays*, of Saccha- 

 rum officinale, &c., which sometimes grow into hairs, but in 

 most cases remain undeveloped. And this is undoubtedly the 

 case in the Nymphace, for some of them exhibit in their de- 

 veloped state hairy under surfaces of the leaf. 



The examination of the leaves of Pleurothallis ruscifolia in 



various stages of development, which I have only lately been 



able to perform, taught me to correct my error, but also 



showed, that M. Schleiden may in his otherwise highly valuable 



* Pflanzen-Physiologie, i. Tab. V. fig. 20. 



