48 MISSOURI BOTANICAL GARDEN. 
lignin of the sections. Potter does not state at what tem- 
perature his experiments were carried on but it is presum- 
ably at about 100 degrees Centigrade. If his results were 
applicable to woods in general the delignification in the 
present experiment should have been apparent even sooner 
than it actually was; and it should have taken place in all 
or nearly all of the woods instead of but two out of the 
twelve which were used. But we find none of the woods 
were delignified in the time stated by him to be effective 
with the woods tested by him. Apparently then the woods 
used in these experiments are more thoroughly lignified or 
else hold their lignin in combination more firmly than was 
the case with the woods used by Potter. 
The later boiling tests were performed wholly with the 
autoclave at a temperature of about 120 degrees Centi- 
grade. In general it may be said that many of the woods 
gave evidence of delignification after fifteen hours of treat- 
ment, and nearly all, after eighteen hours of steaming. 
Sequoia Wellingtonia, Betula lutea and Juglans nigra 
gave no results so far as could be detected, but it is barely 
possible that these woods are dark colored enough so that 
the reaction was not seen even if obtained. 
SOLUBILITY OF LIGNIN IN SPRING AND SUMMER WOOD. 
An experiment was next tried to test the relative solu- 
bility of the lignin of the early and late wood of the annual 
rings. For this purpose a wood was chosen which showed 
a decided difference between the two parts of the ring. 
Pinus palustris seemed to be very good, having a decided 
difference in the thickness of the fiber walls of the spring 
and summer wood, and also being entirely free of unlignified 
cellulose. Microscopic sections were cut from fresh wood 
and boiled in the manner above indicated. After a very 
long period of boiling, a record of which was unfortunately 
not kept, it was found that the spring wood seemed to be 
