FORMS OF CELLS. 
43 
irregular in outline, sometimes even branching. The 
walls are distinctly lamellated, and they give the char- 
acteristic reaction for lignocellulose with phloroglucin 
and aniline sulphate; occasionally, however, one or 
more of the sides remain unthickened. The pores are 
elliptical or circular on surface view. 
Bast fibers are sclerenchymatous fibers which are asso- 
ciated with sieve cells, and which may, or may not, 
give a pronounced reaction for lignocellulose with 
phloroglucin and aniline sulphate. In transverse 
section they are more or less round or polygonal, 
depending upon whether they are isolated or in 
groups. They vary in diameter and length, and also 
in the thickness of the walls ; while most bast fibers 
are between 1 and 2 mm. in length, they may be more 
than 200 mm. in length, as in Boehmeria nivea. The 
ends may he more or less obtuse, or drawn out to a 
fine point; occasionally they are somewhat branched. 
The pores in surface view are narrow elliptical and 
are arranged according to a left-handed spiral. The 
spiral arrangement of the component substances of the 
wall is supposed to give strength to the fibers and, 
according to Scliwendener, they will sustain a weight 
nearly equivalent to that sustained by wrought iron 
and steel. 
Bast fibers may be isolated by the use of Schulze’s 
macerating fluid, which is prepared by dissolving a 
few crystals of potassium chlorate in nitric acid and 
moderately heating the solution containing the mate- 
rial either on a slide or in a test tube. 
Wood fibers are sclerenchymatous fibers which are 
associated with ducts, and which usually give a more or 
less distinct reaction for lignocellulose. They occur 
more frequently than bast fibers (gentian being one of 
the few drugs in which they are wanting) but seldom 
