DKY-KOT OF INCENSE CEDAE. 
9 
sionally subapplanate, often spuriously stipitate from knot holes, 4 to 15 by 5 to 22 
by 5 to 20 cm., commonly 7 to 10 by 11 to 13 by 8 to 13 cm., occasionally abortive 
■without hymenial layer, then assuming irregular shapes; surface pubescent when young, 
rimose and chalky when old, at first buff, then tan, and often blotched with brown 
when attacked by insects; margin obtuse, frequently having an outer band of darker 
brown, often slightly furrowed; context homogeneous, 1 lemon-yellow, later buff to 
tan, usually darker near the surface when old, slightly bitter to the taste, 4 to 14 cm. 
thick, commonly 9 to 11 cm., usually friable when dry but occasionally becoming 
partially horny, hard; tubes not stratified, lemon-yellow within, cylindric 0.2 to 3 
cm. in length, shorter next the margin, mouths circular or slightly irregular, 1 to 3 
to a millimeter, lemon or sulphur yellow during growth, turning brown when bruised 
or old, becoming lacerate; under surface of the hymenial layer sometimes exuding 
clear yellow drops of liquid, sweetish to taste; spores hyaline or slightly tinged with 
yellowish brown, smooth, ovoid (200) range 3 to 6.5 n by 4.5 to 9 /*; standard size 
3.5 to 4.5 n by 6.5 to 7 /x, nucleated; cystidia none. 
The following table presents detailed measurements of 24 sporo- 
phores of Polyporus amarus: 
Table I. — Sporophore measurements of the incense-cedar dry-rot fungus. 
cm. cm. cm. 
cm. cm. cm. 
cm. cm. cm. 
3. 8 by 4. 8 by 8.3 
8. by 13. by 13. 
9. 5 by 17.0 by 13. 3 
4. 2 by 5. 5 by 5.5 
9.0 by 11. 5 by 9.9 
9. 8 by 13. 2 by 13.0 
6.0 by 7. 3 by 8.6 
9.0 by 10.0 by 10.0 
10. 3 by 14. 9 by 14. 8 
6. 8 by 11. 2 by 12.3 
9.0 by 10. 5 by 11.0 
11. 4 by 20. 7 by 19. 8 
7. 5 by 11. 4 by 9.0 
9.0 by 13. 3 by 12.0 
12.0 by 16. 4 by 10. 8 
7. 5 by 17.0 by 8.1 
9.1 by 10. 7 by 8.5 
12. 1 by 21. 2 by 12. 5 
7. 6 by 11. 4 by 9.5 
9.1 by 12. 4 by 8.9 
14. 5 by 22. by 13. 
8. by 12. 5 by 10. 
9. 5 by 14. 7 by 11.0 
14. 8 by 12. 7 by 16. 5 
The sporophores, which last for one season only even at best, are 
not at all common, a statement which is supported by the number 
of years the dry-rot was known before the cause was definitely 
determined. During certain years sporophores seem to be very 
rare. They most commonly occur in the summer, and especially 
in the fall, but occasionally are found at other seasons. Observa- 
tions record two fresh ones in March in a rather mild climate at an 
altitude of about 3,000 feet in the Sierra Nevada. Another was 
found in a different locality in June. No sporophores have been 
found developing later than October, but occasional fresh ones 
may be carried over from a previous fall into the winter in a frozen 
condition. They are then destroyed in the spring. 
Typically the sporophores are produced on living trees but are, 
on occasions, found on dead fallen trees. (PL I.) Seven such cases 
have been observed during the past five years. In five of these it 
was possible to determine the time which elapsed between the felling 
of the tree and the appearance of the sporophore. Three of the 
sporophores were produced 3 years, one 4 years, and one 27 years 
after the trees had been cut. As to how long the mycelium may 
i The substance of the sporophore not including the outer layers. 
182803°— 20— Bull. 871 2 
