1895.] The Crystallization of Cellulose. 17 
In his discussion the author uses the term cellulose to des- 
ignate provisionally the carbohydrate or carbohydrates of the 
cell wall that are insoluble in acids and alkalies and give the 
blue color with iodine and sulfuric acid. 
For the author’s method of obtaining the so-called crystals 
of cellulose, we may describe the course pursued for the root 
of the beet (Beta vulgaris), which is only modified in individual 
cases depending upon the resistance of the tissue at hand. 
Moderately thick sections of the swollen root were — (1) 
soaked in 1% KOH (or eau de javelle) to dissolve out the cell 
contents. In repeating his experiments in the Johns Hopkins 
laboratory half an hour in 1.5% KOH was generally found 
‘sufficient. (2) After thoroughly washing in distilled water 
. the sections were put into Schweizer’s reagent for four or five 
hours. (3) The dissolved cellulose is precipitated in crystals 
by putting the sections after removal from Schweizer’s reagent 
into ammonia, the size of the crystals being said to vary with 
the strength of the ammonia, 5% giving only spherocrystals, 
and 20% giving beautiful arborescent or radially arranged 
spicular crystals. 
These bodies, which have the appearance of crystals under 
the microscope, can be seen best after clearing the sec- 
tions of copper compounds by washing them with water and 
treating with dilute HCl and then coloring them with chlor- 
lodide of zinc (or Congo red before treatment with HCl). 
They are then found almost entirely within the cell walls, 
Sometimes in the intercellular spaces, those that are formed 
outside being from the cells opened in cutting the section, 
very little of the dissolved cellulose diffusing through the cell 
wall. If the Schweizer's fluid has acted long enough the 
lodine reagents give no evidence of any cellulose remaining 
In the cell membrane, the only blue coloring substance being 
the crystals within the cell cavity. 
It is from the beet evidently that Gilson gets his most 
characteristic crystals, as it is these that he figures for his 
article, though he has worked in this way upon sections of 
More than fifty plants. Most of these are angiosperms, but 
among them are chara and spirogyra of the alge, and mucor 
and agaricus of the fungi, with half a dozen mosses and ferns 
and two gymnosperms. In all of these, except the fungi, he 
Was able to get satisfactory crystals of cellulose, and has also 
obtained good results with a number of seeds, such as coffea, 
*—Vol. XX.—No. 1. 
