honey-combed surface or from
between the teeth of those sorts with a spiny under surface. If the caps
were so arranged that the fruiting surface came to be on the upper side,
the larger number of the spores would lodge in the crevices between the
extensions of the fruiting surface. Singularly, this position of the
fruiting surface does occur in the case of one genus with a few small
species.

Interesting examples of the operation of this law are sometimes met with
in abandoned coal mines, or more frequently in the woods. In abandoned
mines the mushrooms sometimes grow from the mycelium which spreads out
on the rock roof overhead. The rock roof prevents the plant from growing
upright, and in growing laterally the weight of the plant together with
the slight hold it can obtain on the solid rock causes it to hang
downward. The end of the stem then curves upward so that the pileus is
brought in a horizontal position. I have seen this in the case of
_Coprinus micaceus_ several times.

[Illustration: FIGURE 15.--Polyporus applanatus. From this view the
larger cap is in the normal position in which it grew on the standing
tree. Turn one fourth way round to the right for position of the plant
after the tree fell. (1/6 natural size.)]

In the woods, especially in the case of the perennial shelving fungi,
interesting cases are met with. Figure 15 illustrates one of these
peculiar forms of _Polyporus (Fomes) applanatus_. This is the species so
often collected as a "curio," and on account of its very white under
surface is much used for etching various figures. In the figure the
larger cap which is horizontal represents the position of the plant when
on the standing maple trunk. When the tree fell the shelf was brought
into a perpendicular position. The fungus continued to grow, but its
substance being hard and woody it cannot turn as the mushroom can.
Instead, it now grows in such a way as to form several new caps, all
horizontal, i. e., parallel with the surface of the earth, but
perpendicular to the old shelf. If the page is turned one-fourth way
round the figure will be brought in the position of the plant when it
was growing on the fallen log.

[Illustration: PLATE 3, FIGURE 16.--Daedalea ambigua. Upper right-hand
shows normal plant in normal position when on tree. Upper left-hand
shows abnormal plant with the large cap in normal position when growing
on standing tree. Lower plant shows same plant in position after the
t