Meyen's Report for 1839 on Physiological Botany. 255 



the number of the ligneous bundles which have been formed 

 by the above-mentioned division. 



M. Schleiden has published ' Botanical Notices ' (Wieg- 

 mann's Archiv, i. p. 211), in which several points of anatomy 

 and physiology are treated of; 1 must refer the reader to the 

 original treatise. 



Observations on the presence of certain assimilated and secreted 

 substances in Plants. 



M. Morren* has published a short memoir on the presence 

 of fatty and volatile oils in the cellular tissue of different 

 plants, wherein attention is directed to several new facts. 

 The author first gives a view of the results of observations on 

 this subject, extracted from my works, and mentions that fatty 

 or fixed oils are only formed within the cells, while the aethe- 

 real oils make their appearance in peculiar, more complicated 

 organs, as in glands, oil-channels, &c. M. Morren says, that 

 from this one might believe that the aethereal oils, on account 

 of their many peculiarities, are more perfectly elaborated, and 

 therefore require peculiar organs for their formation, while the 

 simple fatty oils are produced in the common cells. However 

 these statements are not complete, for in my ' Physiology/ 

 vol. ii. p. 493, it is stated expressly, " The secretion of these 

 volatile oils takes place in peculiar glands, either simple or 

 compound ; but in greater quantity in the internal glands. 

 In general however the volatile oil is deposited in the common 

 cells of the different parts of the plant, where it appears in the 

 sap more or less plainly in the form of small oily drops or even 

 in large masses. This is almost always the case in the petals, 

 and it is very rare that the oil is secreted in internal glands. 5 ' 

 M. Morren observed the presence of drops of an aethereal oil 

 in the cells of the epidermis of the stamens of Sparmamiia 

 africana, where it was first yellow and afterwards became 

 red, and it is stated, that during the formation of this oil, the 

 walls of the cells became thickened. Also in the cells of the 

 epidermis of the upper surface of the leaf of Ophrys ovata, M. 

 Morren found an aethereal oil, but it appears that it is only 

 there during the time the plant is in blossom. [In another of 

 the Orchidece, namely, in Pleurothallis ruscifolia, in the cells 

 of the upper epidermis of the leaves, I have observed an oil, 

 which had some similarity with a fatty oil. — Mey.~\ For at a 

 later period M. Morren could not discover it, and therefore 

 he says that these observations prove to a certainty that the 

 aethereal oil is formed in the cells and preserved there some 



* Bulletin de l'Acad. Row de Bruxelles, vi. No. 6. 



