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STUDIES ON THE LIGNIN AND CELLULOSE OF woop. 47 
It consisted of an inner, lining, layer which was not as 
thick as was that of the Populus species. 
Later and more protracted examination of the other 
woods showed cellulose to be present in small quantities 
in a single ring of the wood of Acer Pennsylvanicum. It 
was also noted in wood of Acer saccharinum, Catalpa 
speciosa, Nyssa aquatica, Pinus Taeda, Platanus occt- 
dentalis and Ulmus Americana. It was present in all of 
these only in small quantities. 
BOILING TESTS. 
The boiling tests were performed as follows: transverse 
and longitudinal sections of the wood were cut, placed in 
distilled water in sterile test-tubes, and boiled in an Arnold 
sterilizer for two or three hours per day in a manner sim- 
ilar to that commonly used in the discontinuous steriliza- 
tion of culture media. Attention is here drawn to the fact 
that the temperature reached in tbe Arnold sterilizer is 
‘about 100 degrees Centigrade. The boiling was continued 
until a total of twenty hours had been attained. The tubes 
were then placed in an autoclave and steamed at a pressure 
of about sixteen pounds and a temperature of about 120 
degrees Centigrade.. This steaming in the autoclave was 
continued until forty hours of boiling had been accom- 
plished. 
After fifteen hours of boiling i in the Arnold sterilizer a 
faint appearance of delignification was perceived in the 
sections of Sassafras Sassafras. 'Twenty hours of boiling 
made it very pronounced. See plate 2, figures 3 and 4. 
After seven hours in the autoclave, or a total of twenty- 
seven hours of boiling, the sections of Picea rubens also 
showed a light blue reaction in the inner lignified layer of 
the fiber walls when treated with chlor-iodide of zinc. 
See plate 2, figure 1. With these two exceptions the 
forty hours of boiling seemed to have no effect upon the 
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