9O Cellulose 



fibres, notably the woods of which the characteristic non- 

 cellulose constituent is a R. hexene derivative. 



Pectocelluloses and Mucocelluloses. Comprising a 

 wide range of tissue constituents of which the non-cellulose 

 constituents are colloidal forms of the carbohydrates, or closely 

 allied derivatives, easily converted by hydrolytic treatments into 

 soluble derivatives of lower molecular weight, and belonging 

 to the series of ' pectic ' compounds, or hexoses, &c. 



Adipocelluloses and Cutocelluloses. The substance 

 of cuticular and suberised tissues in which the cellulose is 

 associated with fatty and waxy bodies of high molecular weight. 



To deal with these groups in detail would involve a survey 

 of the entire vegetable kingdom ; of which, on the other hand, 

 but a very small section has been subjected to systematic 

 investigation. It is true, of course, that an immense number 

 of proximate analyses of vegetable products have been put 

 upon record ; but the analytical methods adopted have been of 

 the empirical order, and their results, stated under such terms 

 as * crude fibre/ * non-nitrogenous extractive matters,' cannot 

 be regarded as 'systematic' in the sense of constitutional 

 diagnosis. We shall therefore confine ourselves to an account 

 of typical members of the above groups, and such as have been 

 investigated by molecular, as opposed to statistical methods. 



Fre*my has devised (Compt. Rend. 83, 1136) a system ol 

 chemical differentiation and classification of vegetable tissue con- 

 stituents, which, although it has found but little favour, and is in 

 fact generally rejected, by critical writers on this subject, may be 

 briefly noted here. 



The classification embraces (a) celluloses, including ' para- 

 cellulose' and * metacellulose ' in addition to the normal cellulose ; 

 (b) vasculose ; (c) cutose ; (d} pectose and pectic compounds ; and 

 (e) nitrogenous bodies. 



The celluloses (a) are differentiated by treatment with the 

 cuprammonium reagent : * cellulose' dissolves directly ; * para- 



