18 BOTANICAL GAZETTE [JULY 
The contents of the medullary ray cells are stained by acid 
brown. Both the walls and the cell contents are deeply stained 
by methylene blue as well as by ruthenium red. 
The results as to the tissues just described agree closely with 
those obtained for Pinus. The cambium walls and the middle 
lamellae of the xylem and medullary ray walls are of pectic 
nature; the remaining layers of the xylem and medullary ray 
walls are composed of a mixture of pectic and nitrogenous sub- 
stances, the pectic constituents being perhaps predominant in 
the medullary rays; and there is evidence of the presence of a 
small proportion of cellulose in these thickening layers. 
The bast fibers, when treated with ruthenium red, show a 
peculiar and most beautiful differential stain. It is most clearly 
brought out after treatment with acid alcohol, though it appears 
in sections not so treated. The middle lamella, which is rela- 
tively very thin, is deeply stained. It is sharply distinguished 
from the layer next within it on either side, which is colorless or 
very slightly stained. Next, passing toward the interior of the 
cell, comes a layer with a little color, then one a little more 
deeply stained, and so on, the depth of stain increasing until the 
last thickening layer, reaching almost to the center of the cell, 
is colored to about the same degree as the middle lamella. It 
should be noted that the stain shown in these walls is rather a 
purplish-red than the bright red commonly found in ruthenium 
red preparations. This behavior with ruthenium red is markedly 
different from that shown by Dippel (2) in his figure 139, in 
which all the wall of the bast fibers except the middle lamella is 
shown as unstained. On page 219, he mentions, as an instance 
of pectose-free cell walls, the bast fibers of Merium Oleander. 
This is plainly an error. 
The bast fibers are not stained at all by exposure for a few 
seconds to methylene blue. By methyl violet B (three or four 
minutes), the middle lamella of the bast and the other wall lay- 
ers except those next the middle lamella are stained violet. 
Acid brown has an effect exactly opposite to that of ruthenium 
red; that is, the middle lamella is not stained; the next layer is 
