BULLETIN OF THE BUSSEY INSTITUTION. 409 
No. 36. — Laboratory Notes. By F. H. Srorer, Professor 
of Agricultural Chemistry. 
A. Doty Birch Wood yields little Wood-Gum.— Since the evi- 
dence thus far accumulated tends to show that the hemicellulose 
xylan (wood-gum) in the trunks of trees is comparatively speaking 
difficult of digestion and less active, physiologically speaking, than 
the true cellulose with which it’ is accompanied and combined it 
might well be possible that doty, decaying or decayed wood should 
yield more wood-gum to alkaline lyes than can be obtained from 
the sound wood. 
On subjecting this idea to the test of experiment it was found 
to be untenable, at least in so far as concerns doty wood of the 
Gray Birch (Betula populifolia of Aiton). 
Two samples of dead and decaying birch wood were collected in 
January. The first specimen was an excellent example of doty 
wood. It was from the trunk of a tree thirteen inches in circum- 
ference, the outer bark of which was in place and undecomposed. 
The wood was almost white, as to its color and looked like pith; 
it was light and punky and so brittle that when dry it could 
readily be crumbled between the fingers. Although the shape of 
the original bough was retained, the material had lost all semblance 
of strength or solidity excepting at the innermost heart which con- 
sisted of a thin core of tolerably firm wood. 
The second sample was much more thoroughly decayed than the 
first. It was from a bough three inches in diameter. On remoy- 
ing the outer bark, which was well preserved, there was found 
within a soft spongy mass of dark, decayed wood which crumbled 
to powder readily between the fingers. All parts of the material 
seemed to be equally decayed, though at some time it had been 
infested with worms whose borings could readily be traced since 
they were filled with a brown powder, 7. e., the indigestible matter 
rejected by the worms. This powder was scraped out from the 
worm-holes and rejected, while the rotten wood REQD SE was dried 
and powdered. 
It is to be remarked of these two examples that the first was a 
much better specimen than the second, and that the results obtained 
on analyzing the first sample were more intelligible and more satis- 
factory. Had it not been that the second sample yielded a fairly 
