94 College of Forestry 
however, should be preceded by a study of sections of normal 
wood treated with these respective reagents in order to deter- 
mine the relative degree of lignification of the various woody 
elements and any structural peculiarities that would aid 
materially in explaining the course of the deeay in the wood. 
Normal wood, when treated with chlorzinc-iodine, shows 
the presence of considerable cellulose. The middle lamellee 
of all the cell-walls become colored golden brown. The wood 
prosenchyma elements are peculiar in that the tertiary layers 
(layers bordering on the cell lumina) assume a pronounced 
violet coloration “which extends into the secondary layer but 
is only faintly perceptible in the primary layer or middle 
lamella. The violet coloration assumed by the tertiary layer of 
the wood prosenchyma cells, however, diminishes in intensity 
toward the outer margin of the growth ring until it is scarcely 
discernible in the elements of the pammierwaod: The vessels, 
pith-ray cells, and thin-walled wood parenchyma fibers ex- 
hibit only a golden brown coloration with chlorzinc-iodine. 
Tests for vee etaan were made with phloroglucin-HCl, 
aniline sulphate- TH.SO,, resorein-HCl, phenol-HCl, orein- 
TiC], and thymol-ICl, each reagent exhibiting its respective 
color reaction throughout. 
In sections of wood treated with phloroglucin-HCl the 
vessel walls and middle lamellee of all the cells are stained 
most strongly, becoming old rose or wine-colored. The col- 
oration assumed by the middle lamelle is especially pro- 
nounced in the terminal cells of the growth ring. The 
remaining layers of the medullary ray and wood parenchyma 
cells also become rose-colored. The secondary and tertiary 
layers of the prosenchyma elements are colored almost uni- 
formly rosy-violet — at least they are considerably: lighter 
than their middle lamellae. When sections are treated with 
aniline sulphate-H.SO, the vessel walls and the middle 
lamelle of all the cells stain most deeply, becoming golden 
yellow. The remaining layers of the medullary ray and 
wood parenchyma cells stain only to a pale lemon color. The 
secondary and tertiary layers of the prosenchyma elements 
remain quite pale in contrast to their middle lamelle, they 
