he very common mould called
_Cladosporium herbarum_ is constituted as conidia, and of this again
_Macrosporium sarcinula_, Berk., is considered to be another
condition. In the next place, _Cytispora orbicularis_, Berk., and
_Phoma herbarum_, West., are regarded as pycnidia, enclosing
stylospores. Then _Alternaria tenuis_, Pr.,[n] which is said to be
parasitic on _Cladosporium herbarum_, is held to be only a form of
that species, so that here we have (including the _perithecia_) no
less than six forms or phases for the same fungus. As _Macrosporium
Cheiranthi_, Pr., often is found in company with _Cladosporium
herbarum_, that is also open to suspicion.

We have adduced in the foregoing pages a few instances which will
serve to illustrate the polymorphism of fungi. Some of these it will
be observed are accepted as beyond doubt, occurring as they do in
intimate relationship with each other. Others are considered as
scarcely so well established, but probable, although developed
sometimes on different species of plants. Finally, some are regarded
as hitherto not satisfactorily proved, or, it may be, only suspicious.
In this latter group, however much probability may be in their favour,
it can hardly be deemed philosophical to accept them on such slender
evidence as in some cases alone is afforded. It would not have been
difficult to have extended the latter group considerably by the
addition of instances enumerated by various mycologists in their works
without any explanation of the data upon which their conclusions have
been founded. In fact, altogether this chapter must be accepted as
illustrative and suggestive, but by no means as exhaustive.

[A] De Bary, in "Quarterly German Magazine" (1872), p. 197.

[B] The method pursued by Messrs. Berkeley and Hoffmann of
surrounding the drop of fluid, in which a definite number of
spores or yeast globules had been placed, with a pellicle of
air, into which the germinating threads might pass and
fructify, is perhaps the most satisfactory that has been
adopted, though it requires nice manipulation. If carefully
managed, the result is irrefragable, though doubts have been
cast, without any reason, on their observations.

[C] De Bary, "Uber die Brandpilze" (Berlin, 1853), pl. iv. figs. 3,
4, 5.

[D] A. de Bary, on Mildew and Fermentation, in "Quarterly German
Magazine," vol. ii. 1872.

[E] Berkeley, "