The crystallization of cellulose. 
DUNCAN S. JOHNSON. 
Previous investigation. 
In number two of volume nine of La Cellule, Eugene Gilson 
of the University of Gand has an interesting article on ‘*The 
crystallization of cellulose and the chemical composition of the 
cell membrane of plants.” 
I will give an abstract of the article and then have some- 
thing to say of some work in the same line done in the winter 
and spring of 1894 in the biological laboratory of Johns Hop- 
ins University. 
The author first sets forth the present state of our knowl- 
edge of the constitution of the cell wall, taking the work of 
Schultze as the most authoritative. Schultze holds that we 
have in the cell wall dextrocellulose and mannosocellulose. 
These two agree in being insoluble in dilute acids or alkalies 
by boiling and in their coloration by iodine and sulfuric acid, 
but differ in their derived sugars, the first giving only dex- 
trose and the second both dextrose and mannose. Besides 
these he proposes to give the name of hemicelluloses to those 
as yet little known compounds occurring in the cell wall that 
are soluble in dilute acids and alkalies by boiling, and which 
probably agree with dextrocellulose and mannosocellulose in 
their reaction with chloriodide of zinc and iodine and sulfuric 
acid. 
None of these bodies, though closely related to the crystal- _ 
line sugars, have hitherto been considered to be crystalline — 
but rather amorphous. ; 
Gilson hoped to settle the following points: (@) Which of 
the carbohydrates is it that crystallizes from a solution of the 
material of vegetable tissue in Schweizer’s reagent, when 
strong ammonia is added ? (4) Is cellulose a distinct chemical 
individual or are there several compounds in the cell wall that 
are insoluble in dilute acids and alkalies, and give the blue 
color with the iodine reagents? (c) Is the cellulose free or in 
combination in the cell membrane with other constituents? 
(d@) Is the cellulose distributed through all three layers of the 
cell membrane or localized in one or two or in certain parts of 
all? 
[16] 
Set 2 DP 
