XXVIII SCIENCE PROGRESS. 



very great importance from their relationship to the physiological division 

 of labour of which the plant tissues are the seat. 



The authors go very exhaustively into the relation of these bodies 

 to pure cellulose and establish the view that the latter is the antecedent 

 of them all, being converted chemically into them. The hypothesis 

 therefore of the formation of lignin, suberin, etc., in the cell and its wall 

 becoming impregnated with them by some kind of infiltration is no 

 longer tenable. The question, however, of the details of the transfor- 

 mations, or even whether they came from pure cellulose or some 

 compound built up with it in the ordinary course of elaboration, the 

 authors prefer for the present to leave undecided. 



Perhaps the most interesting part of the volume, both to the 

 student and the general reader, is the section dealing with the applica- 

 tions of cellulose in the arts. To the former class of readers, pages 

 243-273 will appeal very strongly, as the authors give very valuable 

 laboratory and research notes dealing with the separation of cellulose 

 from the various vegetable tissues, the methods of analysis, the char- 

 acters of cellulose compounds, etc. The latter portion of the volume 

 is more adapted for general reading, as it embraces a summary of the 

 economic uses of the material. Many of the criticisms of the writers 

 on these points are of the greatest value, particularly the section 

 devoted to the consideration of the manufacture of paper from different 

 celluloses. A fuller examination of these points is beyond the scope of 

 the present notice, but the section in question brings out very grave 

 considerations as to the permanence of many of our records. 



The book is illustrated by fourteen plates which are reproductions 

 of microphotographs of sections showing the sources of most of the 

 celluloses of commerce. 



