12 BOTANICAL GAZETTE [JULY 
and agrees with results generally noted in tissues of spermato- 
phytes. 
PINUS SILVESTRIS. 
Sections of young twigs and branches cut in the fall were 
used ; these, therefore, were past the season of rapid cam bial 
division, and the cambium cells were in a condition of compara- 
tive rest. Sections of old and seasoned pine wood were also 
used for comparison with the young tissues. 
In cross sections through the cambium and neighboring 
tissues of young wood, treated with acid alcohol as above 
described, the cambium walls are stained throughout their thick- 
ness by methylene blue a deep and apparently uniform blue. 
The result is similar in sections not previously treated with 
acid alcohol. 
Similar cross sections, both in the fresh condition and after 
treatment with acid alcohol, were stained with ruthenium red. 
This stain is also taken up freely by the cambium walls. The 
radial walls are noticeably thicker than the tangential. In the 
middle of the radial walls there is often a less deeply staining 
layer, recognizable as Dippel’s Zwischensubstanz. The rest of 
the walls are deeply stained, except that in many of the older 
cambium cells, whose walls are thicker than those of the young- 
est cells present, there is, next the cell interior, a light line indi- 
cating a later deposited, unstained, or less deeply stained wall 
layer. The corners where radial and tangential walls join are 
especially deeply stained. In many cases, a continuation of the 
radial cambium wall into the middle lamella of the xylem and 
bast can easily be traced. 
A difference in depth of stain between radial and tangential 
walls similar to that given by methylene blue is found in the 
longitudinal sections treated with acid alcohol and exposed for 
a few minutes to the action of Bismarck brown. 
In cross sections treated with acid alcohol and Stained one 
hour with fuchsin, the cambium walls are uncolored; the proto- 
plasmic contents of some of the cambium cells are stained red. 
The difference between the affinity of these walls for Bismarck 
