THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY, 



No. 98. APRIL 1845. 



XXVII. — On the Penetration of the Cuticle into the Stomata. 

 By Hugo von Mohl*. 



Three observers have nearly at the same time, and perfectly 

 independent of one another, discussed a point which, notwith- 

 standing the numerous investigations made respecting the sto- 

 mata, had hitherto been entirely overlooked in their anatomy; 

 they are, however, far from agreeing in the descriptions they give 

 of the circumstance discovered by them. 



Gugliemo Gasparrinif states, that beneath the stomata of the 

 stem of Cactea, in particular of Cereus peruvianus, of the stem 

 of Euphorbia officinarum, and of herbaceous leaves, there is situ- 

 ated a vesicular organ, which he terms Cistoma. Its walls are 

 said to consist of delicate fibres connected by a membrane, which 

 form a sphincter at the upper end of the cistoma, situated beneath 

 the closed aperture of the stoma. The vesicular organs the 

 author separated with the cuticle from the epidermis by boiling 

 the latter in dilute nitric acid. 



Hartig, in his ' Lehrbuch der Pflanzenkunde,' part 4, 1843, 

 describes the same organ as an appendage of the cuticle. To the 

 latter he ascribes a very complicated structure, separating it into 

 three diiFerent layers: 1. an external membrane , epichroa; 2. an 

 internal membrane, endochroa; 3. a central mass situated between 

 these membranes, the central cement, mesocolla. It is stated of 

 the external membrane, that it extends over the entire leaf, pene- 

 trates into the area in front of the stomata, but nevertheless con- 

 tinues further over the stoma itself without interruption, while 

 the inner membrane is immersed in the form of folds between 

 the cells of the epidermis and penetrates in various plants, more 

 or less deeply into the subjacent cellular tissue, in which case it 

 then takes its course through the intercellular passages in the 

 form of vessels {intercellular vessels). In like manner the inner 



* From the Botanische Zeitung for Jan. 3, 1845, Translated and com- 

 municated by W. Francis, Ph.D., F.L.S. 



t Rendiconto delle adunanze e dei lavori dell' Academia delle Scienze, 

 Napoli, 1842. 



Ann. ^ Mag. N. Hist. VoLxy. H 



