VARIATIONS OF FUNGI.

57

those instances in which it is accidentally formed on the uppersurface, how much it is modified. There are, however, manyof the lower species in which it is superior, in which case thehymenium is said to he resupinate. This character is nothowever constant, for when the substance on which theFungus grows is placed in peculiar conditions, the edge of thepatch will become detached, and will follow the common lawof turning its hymenium away from the light, and thus froma resupinate will have become a reflected, or even a dimidi-ate Fungus. The contrary process sometimes takes place, bywhich dimidiate species become resupinate, insomuch that avast quantity of resupinate Polypori are referable, when pro-perly understood, to higher species. Even some Agarics areresupinate, but these occasionally turn away their hymeniumfrom the light, or on the contrary the pileus which was at firstshortly stipitate becomes gradually excentric and turns over,exposing the hymenium. The tendency amongst the higherHymenomycetes is so strong to produce the hymenium on thelower side, that in some cases, especially in the genus Poly-porus, if the plant be accidentally reversed, the hymenium isgradually obliterated, and a new hymenium formed on theother surface. In consequence, where Polypori are in veryvigorous growth, it is often difficult to preserve them in anatural state. A little change of situation completely oblite-rates the orifices of the pores, and if an hymenium be formedabove, tlie whole characters of the plant are altered.

Not only do many Fungi remain long in the state of spawnwithout forming fruit, but they give rise occasionally to pro-ductions quite at variance with the characters of the perfectplant. Hence a number of spurious genera and species ori-ginate which are justly struck out of every scientific Flora.The genus Rhizomorpha, for instance (as mentioned above,p. 42), where it is really fungoid, consists, except in a solitary