.9$ BOTANICAL MICROTECHNIQUE. 



For the preservation of plants containing solanin, Wotht- 

 schall (I, 1 86) recommends simply drying them. 



o. Syringin, C 17 H 24 O 9 + H 3 O. 



163. Syringin occurs, according to Borscow (I, 36), in 

 branches of Syringa vulgaris within the thick-walled ele- 

 ments of the phloem and of the xylem, as well as in the 

 medullary rays, but only in the cell-walls. For its micro- 

 chemical recognition this author uses a mixture of one part 

 concentrated sulphuric acid and two parts water. This is 

 added to delicate longitudinal or transverse sections and 

 colors the walls containing syringin first yellowish green, 

 after a few minutes blue, and finally violet-red. 



p. Glucoside (?) from the Stimulus-conducting Tissue of 

 Mimosa pudica. 



164. Haberlandt (I, 17) has observed that when the stem 

 or petiole of Mimosa pudica is cut, the drops of fluid which 

 escape leave, on drying, a considerable quantity of a crys- 

 tallized substance whose composition has not yet been made 

 out, but which should be for the present included among 

 the glucosides, on account of its reactions. 



The crystals of this substance are always colored pale 

 brownish and show very various forms. They sometimes 

 form large prisms or cross-shaped twins, sometimes gland- 

 like masses or dendritic bodies ; and sphaeritic formations 

 have been seen. The material identity of these different 

 formations is shown by the fact that they all dissolve with a 

 red-violet color in ferric chloride. They are also soluble in 

 water, but very slightly so in alcohol, and quite or almost 

 quite insoluble in ether. They are dissolved by concen- 

 trated sulphuric acid with a yellow-green color, which be- 

 comes red-brown on warming. Dilute sulphuric and hydro- 

 chloric acids throw down from the aqueous solution a finely 

 granular white precipitate, which is soluble in alcohol. 

 Ferrous sulphate causes a deep rust-red color. Lead-acetate 

 produces a heavy yellow precipitate in the aqueous solution, 



