1884.] of the cell-wall and middle lamella. 95 



• Among other valuable points we may notice that there is some 

 definite evidence that the walls of fungi consist of a framework 

 of cellulose and a large remaining portion of metacellulose. Again 

 the suberin of Chevreul 1 is shown not to be a definite body, but 

 a mixture of cutose and vasculose, and the suberic acid of Doep- 

 ping 2 is derived from the cutose: the vasculose giving rise to the 

 resinous acids. Thus cork consists of a cellulose framework and 

 a remaining portion of cutose and vasculose, and we at once 

 understand how that by the action of such a powerful oxidizing 

 agent as Schultze's mixture, all but the cellulose framework is 

 rendered soluble. It is of interest also to note that when heated 

 with potash, cellulose gives rise to acetic and oxalic, and vas- 

 culose to ulmic acid. 



But although one must be struck by the great value of the 

 researches of Fre*my and Terreil, one cannot I think admit with 

 the former of these investigators, either that by their method a 

 complete analysis of vegetable tissues can be made, or that their 

 various subdivisions include all the substances met with in plant 

 cells. One must regard the research rather in the light of an 

 advance; very definite and very valuable, but still far from com- 

 plete. For instance, it does not appear under what head that 

 peculiar form of cellulose giving a blue with iodine, is to be 

 classed, and especially with regard to the gums and mucilages, 

 it is a question whether they can all be collected under the head 

 of Pectose. As for lignin indeed, there seems to be great pro- 

 bability that, like cellulose, it is a definite substance, but concern- 

 ing gums and mucilages there is every evidence that we have to 

 deal with a class of bodies, the members of which although not 

 very distinct, possess nevertheless many well-marked properties, 

 of sufficient value to admit of their being clearly separated, and 

 in fact, almost every well conducted analysis brings to light fresh 

 forms of mucilage, which differ markedly in some well-defined 

 reaction from the already existing varieties. It now remains for 

 me to dwell shortly on some other points with regard to cellulose, 

 lignin, cutin, and mucilages. 



With the properties of what one may speak of as cellulose 

 proper we are already acquainted. This body exists in an espe- 

 cially pure form, in many palm endosperms, e.g. Bentinckia, 

 Phoenix, &c, and as I have already remarked, usually constitutes 

 the substance of new and unaltered cell-walls. As to how para- 

 cellulose and metacellulose differ from the cellulose par excellence 

 we do not as yet know, and whether the difference consists in 

 oxidation, hydration, or any other change, must for the present 

 be left an open question. Apparently, as far as one can judge 



1 Chevreul (loc. cit.). ~ Doepping (loc. cit.). 



