330 Meyen's Report for 1839 on Physiological Botany. 



nus is mixed with water [to which I also cannot agree. — Mey.~\, 

 and thereby the drops are prevented from coalescing into one 

 single mass. From this fact one might also conclude that the 

 juices which separate within these vessels are of two different 

 kinds, or that the sap, by its action on the plant, is changed 

 partially into one more liquid and transparent, which has ex- 

 actly the appearance of lymph. 5. Lastly, that the walls of 

 the vessels press, by their elasticity, on the sap which they con- 

 tain and drive it towards the opening, just in the same man- 

 ner as a bladder or a gut which is filled very full with water, 

 lets it escape as soon as a puncture is made in its side. M. 

 Savi proceeds to say, that the second phenomenon above- 

 mentioned is easily observed when a small quantity of the 

 resinous sap of Schinus is poured on the surface of water ; we 

 see directly that the sap expands with great celerity into a 

 thin plate or layer ; if small pieces of the dried leaves of any 

 plant be then thrown on this thin oily plate, they are seen 

 to be driven about as by strong impulses, and to move back- 

 wards from the spot on which they were thrown. This pro- 

 perty of expanding itself is common not only to the liquid 

 resin of Schinus, but also to all the Terebinthacece, Euphor- 

 biacea, Urticea, Asclepiadea, and also, according to Carradori, 

 to the fatty and volatile oils. The latter ascribes this pro- 

 perty to the attractive force which is exerted upon the above 

 fluids by water, by which each drop of the liquid on the sur- 

 face is forced to extend itself as far as the cohesive power of 

 the fluid will allow. M. Savi speaks at length on this point ; 

 but the existing facts are quite sufficient to prove that this 

 motion of the Schinus leaves on water is not to be explained 

 by a contractility of the tissue. Finally, I must remark, that 

 the phenomenon with the green parts of Schinus does not 

 always show itself, but only when the plant is in luxuriant 

 growth. 



A paper by Prof. Lindley * was read before the Linnean So- 

 ciety on the anatomy of the roots of the Ophrydece, in which he 

 shows, that salep which is prepared from the roots of certain 

 Ophrydece does not consist chiefly of amylum, as is generally 

 supposed by authors of the present day (?), but that it is com- 

 posed of a substance like bassorin. After Dr. Lindley has 

 mentioned the opinions of the most recent authors, he gives 

 the results of his own microscopical investigations ; from which 

 it appears that the tubes of the Ophrydea universally contain 

 long cartilaginous nodules of a mucilaginous substance which 

 is not coloured by iodine, and also some amylum globules 



* Phil. Mag., vol. xiv. p. 462. 



