Compound Celluloses 91 



cellulose* (epidermis of leaves, &c.) dissolves after boiling with 

 hydrolysing acids ; ' metacellulose ' (found chiefly in lichens) 

 remains insoluble after the acid treatment. 



Vasculose is insoluble in cuprammonium ; it is readily dissolved 

 on heating at high temperatures with solutions of the alkalis. It is 

 attacked by all oxidising agents. It may be selectively attacked 

 by dilute nitric acid. Vasculose is said to abound in hard woods, 

 the hard concretions of pears, &c. It appears to be identical with 

 the lignocellulose of this treatise ; the non-solubility in cupram- 

 monium being a statement of doubtful value. 



Cutose is the substance of the transparent cuticular membrane 

 of leaves &c. It has been further studied by Fremy, and the 

 results of the later investigations are given in this treatise, p. 229. 



Pectose and pectic constituents. These have also been further 

 investigated by Fremy, and his results are noted in connection 

 with the pectocelluloses, p. 216. 



In the main, therefore, the lines of this classification are 

 adopted in this treatise, but that is probably because, and in so 

 far as, they have a physiological basis. Chemically speaking, the 

 classification is of little value, since it rests chiefly upon the actions 

 of hydrolytic agents. Fremy's experimental work, on the other 

 hand, is of a certain empirical value apart from the conclusions 

 drawn from the results; but as it does not contribute to the 

 solution of constitutional problems it will not be reproduced here. 

 An exhaustive account of the researches will be found in Ann. 

 Agron. 9, 529. 



Of the three groups of compound celluloses, the lignocellu- 

 loses stand first in order of importance. Not only are they by 

 far the most widely distributed, but they have a physiological 

 and a. special chemical significance which mark them out as the 

 arena of some of the most interesting processes presented by the 

 many-sided synthetical activity of the plant cell. 



Of the lignocelluloses there are two well-defined types : 

 (i) the bast fibre of the Corchorus species, known in commerce 

 v&jutc ; (2) the woods, i.e. the lignified tissues of perennial 

 stems. The former, being a simple tissue and an annual 

 growth, is a more promising subject for the investigation of the 



