334 FIRST FORMS OF VEGETATION. 
the upper heights; while below the line of perpetual 
snow, on grassy slopes and amid shrubby vegeta- 
tion, may be seen species, if not identical with, at 
least very closely allied to, those of Britain and 
Sweden. One species has been found at a height 
of 18,000 feet, which is probably the highest range 
of fungoid life. 
But while the fungi are, to a certain extent, 
restricted in their geographical distribution within 
certain well-known limits, they are, on the other 
hand, almost ubiquitous in their choice of habi- 
tats. There is hardly a single substance on which 
some species or other of them may not, under 
favourable circumstances, be found.» Asa general 
tule they all grow on dead and decaying organic 
matter, on the mouldering trunks and branches of 
trees and withered plants, and on the bones and 
droppings of animals. But they are also occa- 
sionally found on living trees, and on green leaves, 
and parts of plants that show no symptoms of 
decay. A large class called hypodermous or ento- 
phytic fungi spring from beneath the cuticle of 
living plants. There is hardly a single flowering 
plant which is not infested by them—a different 
fungus being developed upon almost every species. 
Their minute sporules are either directly applied 
to the plants upon which they are found, entering 
by the stomata or breathing pores; or they are 
