224 Cellulose 



The further investigation of the product established in this 

 case the absence of galactose 23\&pentose groups, but the presence 

 of dextrose groups in small proportion. The product of 

 hydrolysis yielded a mixture of osazones in which the deriva- 

 tives of dextrose and mannose appear to be represented. 



But again the constitution of the products of hydrolysis 

 is left in a state of incomplete elucidation. That the authors' 

 methods failed to solve these problems further than has been 

 shown is a further illustration of the complexity of the sub- 

 ject. It is, in fact, the expression of the difficulty invariably 

 experienced with products of the cellulose class, viz. resist- 

 ance to hydrolysis ; and it is from the internal evidence of the 

 difficulties experienced by such practised investigators that 

 we are the more inclined to regard these products, although 

 soluble in water, as cellulose derivatives. 



In regard to other mucilages, we may briefly mention the 

 more important, in order to give some idea of the distribution 

 of these compounds in the plant world. 



AMYLOID is the name applied to a mucilaginous product 

 obtained from the seeds of a number of the Leguminosae, 

 e.g. Tamarindus indica, Hymenaa Courbaril, and Schotia lati- 

 folia (Schleiden, Beitrage z. Botanik, i. 168). It is soluble 

 in boiling water, partly also in cold. It is precipitated by an 

 alcoholic solution of iodine as a blue flocculent mass. 



A similar substance was obtained by Frank (Pringsheim, 

 Jahrb. f. Wiss. Bot. 5, 15) from the membranes of the coty- 

 ledon cells of Tropceolum majus. This product was also 

 definitely proved to be formed at the expense of starch. 



LICHENIN is the soluble constituent of the membranes of 

 Cetraria islandica (' Iceland moss ') and other similar lichens 

 (Knop and Schnedermann, Annalen, 55, 164). It is extracted 

 by treating the plant product with cold dilute hydrochloric acid 

 and adding alcohol to the solution ; or by boiling with water, 



