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The Biology of Polyporus Pargamenus Fries 123 
ring. Bordered pits, either round or elliptical in 1—2 rows, 
more rarely in 1 row only, with large orifices, occur on 
the radial walls of the wood tracheids. According to Pen- 
hallow (Jl. c.) pits also occur on the tangential walls of the 
summer wood tracheids and are rather numerous, prominent, 
and flat. The resin cells or wood parenchyma cells (trans- 
verse section) are rather prominent, being more or- less 
numerous on the outer face of the growth ring and rarely 
zonate. In addition the wood of hemlock normally is char- 
acterized by the absence of resin passages. 
Microchemical Reactions of Normal Wood.— Normal 
hemlock wood treated with chlorzinc-iodine demonstrated 
the presence of comparatively little cellulose, most of the 
coloration being in the late wood. The entire cell-walls of 
the spring tracheids, the pith-ray cells, and the middle 
lamelle of the summer wood tracheids exhibited a brown 
coloration. The tertiary and secondary lamelle of the sum- 
mer wood tracheids, however, did not color brown but 
exhibited a faint violaceous coloration. Evidently the 
reaction for cellulose was obscured by the presence of other 
substances within the cell-walls. In sections that had soaked 
for a time in a mixture of alcohol and glycerine the violet 
coloration exhibited by these layers of the cell-wall was far 
more pronounced. In sections treated with phloroglucin- 
HCl the middle lamelle of all the cells were stained the 
strongest of all, becoming wine-colored. The remaining walis 
of the tracheids in the late wood colored deeply, but less 
strongly that the middle lamelle; they colored to a deep 
reddish-violet. The secondary walls of the early wood 
tracheids assumed a somewhat lighter coloration. The cells 
of the medullary rays are very thin-walled and exhibit the 
same coloration as the tracheids of the early wood. After 
the treatment of sections with aniline sulphate-H.SO, the 
middle lamelle of all the cells again colored most strongly, 
becoming golden yellow. The remaining layers of the late 
wood tracheids likewise were colored golden yellow, but not 
quite so strongly as were the middle lamelle, The golden 
