part 



METHODS FOR THE INVESTIGATION OF THE 

 CELL-WALL AND OF THE VARIOUS CELL- 

 CONTENTS. 



A. The Cell-wall. 



242. SINCE vegetable cell-membranes belong to the class 

 of absorbent bodies and, as their osmotic relations show, 

 can readily give passage to the most various substances 

 which are soluble in water, it may be assumed that they 

 never consist simply of cellulose and water, in the living 

 plant. Rather, they are always incrusted, within the plant,, 

 with a greater or less amount of foreign substances, accord- 

 ing to their age and position. How far the varying chemi- 

 cal and physical relations of vegetable cell-membranes are 

 to be attributed to such incrustations of organic or inorganic 

 nature cannot at present be certainly determined. 



But it is well established by modern researches that pure 

 cellulose is much less than the other constituents in many 

 membranes or parts of membranes. Indeed it is very 

 probable that cellulose is entirely wanting in many parts of 

 membranes. 



Positive conclusions concerning these questions can only 

 be reached when we have obtained, by macroscopic re- 

 searches, a sure means of distinguishing the different con- 

 stituents of the cell-wall. But our knowledge in this re- 

 spect is still too fragmentary to make possible any uniform 



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