10 BOTANICAL GAZETTE [JULY 
pectic compounds stained by it are not decolorized by glycerin 
or alcohol. Ruthenium red, he finds, also stains gums and 
mucilages formed by the decomposition of pectic substances, 
but does not affect decomposition products of cellulose or cal- 
lose. Lignified tissues, not stained by ruthenium red when 
fresh or preserved in alcohol, take it up after treatment with 
alkalies or Javelle water; but their affinity for ruthenium red is 
always less than for certain basic organic stains, such as methyl- 
ene blue, so that by combining its action with that of one of 
the latter class fine double colorations may be obtained. Cuti- 
nized membranes, according to Mangin, are stained in many 
cases, but not the cuticle. Ruthenium red also stains in vary- 
ing degrees the protoplasmic cell contents. 
PTERIS AQUILINA. 
The rhizome was studied-in cross section. In unstained sec- 
tions the middle lamella of the sclerenchyma walls is plainly 
distinguishable from the inner layers by its greater density and 
refractive power. It appears as a dark yellowish-brown layer 
constituting a considerable proportion of the total thickness of 
the wall, enlarged at the angles where three or four cells abut 
into a triangular or quadrangular form, often enclosing at such 
places a similarly shaped intercellular space. 
In the walls of the stone cells, while the absolute thickness 
of the middle lamella is approximately the same as in the » 
sclerenchyma, its thickness relatively to that of the whole wall 
is of course considerably less. Otherwise its appearance is much 
the same as in the sclerenchyma. The canals appear as trans- 
verse lines seeming to pass quite through the wall, including the 
middle lamella. 
On treatment with methylene blue, the sclerenchyma wall is 
colored green, except the middle lamella, which, if stained at 
all, yet appears yellowish-brown in contrast with the other lay- 
ers. The walls of the fundamental parenchyma, as well as the 
protoplasmic cell contents, are stained blue. The parenchyma 
walls are apparently continuous with, and of the same thickness 
