The Biology of Polyporus Pargamenus Fries 129 
become broken up into dissociated fragments, among which 
the lignin reaction persists longest at the cell corners where 
the middle lamellz are the thickest. In time, however, even 
these portions of the middle lamellz become delignified and 
take on a pronounced violet coloration with chlorzinc-iodine. 
Sections of decayed wood are stained permanently with 
aniline safranin and Delafield’s heematoxylin and depict the 
occurrence of lignin and cellulose respectively within the 
cell-walls. In those cell-walls which are still comparatively 
free from decay the middle lamelle stain a bright red while 
the secondary and tertiary lamellz are paler. In adjoining 
cells where the tertiary lamella has been delignified this layer 
appears blue thus indicating the presence of free cellulose. 
In cell-walls that are still further decayed very little red 
(indicating lignified walls) appears and more blue (indicat- 
ing free cellulose) appears on the inner portion of the cell- 
walls. Examination of cells immediately bordering on the 
empty pockets shows that the thickened corners of the middle 
lamelle are the last elements to disappear under the action 
of the fungus. In portions of sections of decayed wood where 
a crumbled mass of fragments is all that remains of a group 
of elements, these thickened corners of the middle lamellz 
may still be seen on account of their bright red color. In 
other parts of this mass of material consisting chiefly of dis- 
sociated remnants of the middle lamellze it can be seen that 
the latter have taken on a blue coloration, thus indicating 
that even that portion of the cell-wall which originally was 
most strongly lignified ultimately has been reduced to free 
cellulose. 
Sections were not made of hemlock wood in an early stage 
of decay where only the springwood was decayed and the 
harder summerwood remained normal. All of the wood 
studied microscopically was in the advanced stages of decay 
and had pockets distributed uniformly throughout the growth 
ring, each pocket being separated by irregular, narrow zones 
of less decayed wood. The medullary ray cells do not appear 
to be dissolved any quicker than the adjoining tracheids. 
In fact within any one pocket or center of decay all the ele- 
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