94 Mr W. Gardiner, On the constitution [Feb. 11, 



Schweitzer's reagent, but soluble in alkalies when subjected to increased 

 pressure, and also dissolved by oxidizing agents as already mentioned, 

 forming resinous acids which saponify with caustic potash. 



Cutose (Cutin). Insoluble in bihydrated sulphuric acid or Schweitzer's 

 reagent, but soluble in alkalies at ordinary pressure. Is converted by 

 nitric acid into suberic acid. 



By taking advantage of these properties, the various substances 

 may be separated from one another. Thus cellulose may be sepa- 

 rated from vasculose by acting upon the tissue either with bihy- 

 drated acid or with Schweitzer's reagent, while vasculose may be 

 removed by the action of cold nitric acid diluted with an equal 

 bulk of water, and subsequent treatment with alkali. Cutose in 

 the same way is soluble in alkali at ordinary pressure. 



Pectose. Insoluble in water, but converted into soluble pectin by 

 the action of acids. 



Calcic pectate. Decomposed by acids, e.g. dilute cold hydrochloric 

 acid. The pectic acid which remains gives with potash a pectate soluble 

 in water. 



Nitrogenous substances. Soluble in potash. 



Inorganic substances. Present in ash. 



As to the occurrence of these substances the authors state that 



Paracellulose is found in epidermal cells in the layers next the 

 cuticle, and in certain cells of roots and other tissues. 



Metacellulose occurs in the tissue of lichens and fungi. The fungin 

 of Braconnot 1 consists largely of this form of cellulose. 



Vasculose. In all lignified tissue. 



Calcic pectate forms the chief constituent of the middle lamella and 

 adjacent layers of many pith cells. In such tissue, a treatment with 

 cold dilute hydrochloric acid causes separation from one another, of the 

 constituent cells. 



Nitrogenous substances embrace probably the remains of the proto- 

 plasm, and in the inorganic salts are included such substances as silica 

 and the like. 



the whole, one would suppose that the gums are derived from the cellulose frame- 

 work, and that the coniferin, which as a glucoside exists probably as a cell- 

 content of wood cells, escapes upon the death of the cell — either naturally or 

 artificially induced — into the cell-wall ; and thus causes a staining of that struc- 

 ture, just as in the case of cells containing tannin. The vanillin one would sup- 

 pose is produced by the subsequent oxidation of the coniferin. It is therefore 

 perhaps, to be regretted that in his translation of Poulsen's Michrochemie (Boston, 

 1884), Prof. Trelease has taken no account of the opinions of Dragendorff andFrdmy, 

 but has stated that " lignin probably consists of (1) vanillin, &c." If we are to 

 regard lignin as the whole collection of the substances, other than cellulose, 

 present in lignified tissues, then Fremy's new name of vasculose — which was other- 

 wise unnecessary — is of value to distinguish the substance -par excellence, which at 

 the present time we usually admit to be present in woody tissue. 

 1 Braconnot (loc. cit.). 



