20 BOTANICAL GAZETTE [JULY 
the corners of the cells there is an angular, less deeply stained 
area enclosed by the middle lamella, just as in the fundamental 
parenchyma of Pteris. 
The effect of ruthenium red on the collenchyma is similar 
to that of methylene blue. The collenchyma walls are not 
stained by acid brown (three or four minutes), but the cell 
contents are deeply colored. The contents are also stained 
brown by acidulated orseille solution, and the walls show a 
brownish tinge, but no distinctive stain for the different layers. 
The cell contents are stained by ponceau (forty minutes), but 
not the walls. 
Acid alcohol sections treated for thirty minutes with aniline- 
water-safranin show a deeper stain in the middle lamella of the 
collenchyma than in the other wall layers. 
The walls of the cork cells are not colored by methylene 
blue nor by acidulated orseille solution. Orseille also does not 
stain the cuticle. 
In acid alcohol sections the middle lamella of the cork cells 
is stained more deeply by aniline-water-safranin (thirty minutes) 
than is the rest of the wall. 
The pith cell walls take up ruthenium red freely, the middle 
lamella, which occupies the greater portion of the thickness of 
_the wall, being deeply stained, especially at the corners. Some- 
times the whole wall appears quite uniformly stained. The 
intercellular spaces are sometimes angular, but very often 
rounded, elliptical, or circular. 
The contents of pith cells are stained by acid brown, the 
walls unstained. The action of orseille is similar. The failure 
of these two stains to affect the pith walls indicates that those 
walls are composed chiefly of pectic compounds, probably in 
purest form in the middle lamella. 
ROSA SP. 
In general, the results were the same as for Nerium. Cross 
sections were treated with acid alcohol and stained with 
ruthenium red. The cambium walls stain quite uniformly 
