6 FUNGI. 
as distinct as in the flowering plants. In fact, there is still no 
reason to dissent, except to a very limited extent, from what 
was written before polymorphism was accredited, that, “with a 
few exceptions only, it may without doubt be asserted that more 
certain species do not exist in any part of the organized world 
than amongst fungi. The same species constantly recur in the 
same places, and a kinds not hitherto detected present them- 
selves, they are either such as are well known in other districts, 
or species which have been overlooked, and which are found on 
better experience to be widely diffused. There is nothing like 
chance about their characters or growth.” * - 
The parasitism of numerous minute species on living and 
growing plants has its parallel even amongst phanerogams in 
the mistletoe and broom-rape and similar species. Amongst 
fungi a large number are thus parasitic, distorting, and in many 
cases ultimately destroying, their host, burrowing within the 
tissues, and causing rust and smut in corn and grasses, or even 
more destructive and injurious in such moulds as those of the 
potato disease and its allies. A still larger number of fungi 
are developed from-decayed or decaying vegetable matter. 
These are found in winter on dead leaves, twigs, branches, 
rotten wood, the remains of herbaceous plants, and soil largely 
charged with disintegrated vegetables. As soon as a plant 
begins to decay it becomes the source of a new vegetation, 
which hastens its destruction, and a new cycle of life vom- 
mences. In these instances, whether'parasitic on living plants 
or developed on dead ones, the source ‘is still vegetable. But 
this is not always the case, so that it cannot be predicated that 
fungi are wholly epiphytal. Some species are always found on 
animal matter, leather, horn, bone, &c., and some affect such 
unpromising substances as minerals, from which it would be 
supposed that no nourishment could be obtained, not only hard 
gravel stones, fragments of rock, but also metals, such as iron 
and lead, of which more may be said when we come to treat of 
the habitats of fungi. Although in general terms fungi may 
be described as “ hysterophytal or epiphytal mycetals deriving 
* Berkeley’s ‘‘ Outlines of British Fungology,” p. 24. 
