VARIATIONS OF FUNGI. 57 



those instances in wliicli it is accidentally formed on the upper 

 surface, how much it is modified. There are, hoAvever, many 

 of the lower species in which it is superior, in which case the 

 hymenium is said to be resupinate. This character is not 

 however constant, for when the substance on which the 

 Fungus grows is placed in peculiar conditions, the edge of the 

 patch will become detached, and will follow the common law 

 of turning its hymenium away from the light, and thus from 

 a resupinate will have become a reflected, or even a dimidi- 

 ate Fungus. The contrary process sometimes takes place, by 

 which dimidiate species become resupinate, insomuch that a 

 vast quantity of resupinate Polypori are referable, when pro- 

 perl}'^ understood, to higher species. Even some Agarics are 

 resupinate, but these occasionally turn away their hymenium 

 from the light, or on the contrary the jnleus which was at first 

 shortly stipitate becomes gradually excentrie and turns over, 

 exposing the hymenium. The tendency amongst the higher 

 Hymtniomycetes is so strong to produce the hymenium on the 

 lower side, that in some cases, especially in the genus PoJy- 

 porus, if the plant be accidentally reversed, the hymenium is 

 gradually obliterated, and a new hymenium formed on the 

 other surface. In consequence, where Polypori are in very 

 vigorous growth, it is often difficult to preserve them in a 

 natural state. A little change of situation completely oblite- 

 rates the orifices of the pores, and if an hymenium be formed 

 above, the whole characters of the plant are altered. 



Not only do many Fungi remain long in the state of spawn 

 without forming fruit, but they give rise occasionally to pro- 

 ductions quite at variance with the characters of the perfect 

 plant. 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 solitarv 



