POLYMORPHIC FUNGI. 
Br M. C. COOKE, M.A. 
[PLATE LX VIII.] 
I T is now generally admitted that a great many fungi, for- 
merly regarded as good and distinct species, are, in reality, 
only conditions or stages of other forms. It has been proved 
beyond doubt that many species of fungi are truly polymor- 
phic, appearing under different phases. It is, notwithstanding 
all this, most premature and unjustifiable to conclude, as some 
have done, that there are no good species at all, or that there 
is no certainty whatever in the study. Whilst admitting that 
many of our old notions have been overturned, that what at 
one time we hardly deemed possible has been proved to take 
place, we are not prepared to go the length of some, whose 
knowledge of the subject falls far short of their assumption. 
It is not very long since that one writer gravely asserted his 
opinion that all the British species of AEciclium , for instance, 
would be reduced to a single species ; that, in fact, there was 
no sound specific distinction between them. This opinion 
originated probably rather in prejudice than as the result of 
study and investigation. Others have lumped together a host 
of unassociated species, without satisfactory evidence, and 
declared them to be only the same thing under different con- 
ditions. Hasty generalisations in this, as in other cases, 
produce more harm than good. 
It is exceedingly difficult to trace such minute organisms as 
fungi, especially moulds, and to prove, without doubt, that 
they are conditions, the one of the other. It is easy enough to 
sow the spores of a certain Mucedine on paste, or potato, or 
any other matrix, cover them carefully, and watch the result ; 
then, if the common Aspergillus or Penicillium makes its 
appearance, to some minds it is at once conclusive that the 
said Mucedine is only a condition of Aspergillus or Penicil- 
lium. Such a conclusion is not only rash, but mischievous, 
and far from the truth. There is no evidence that the Asper- 
