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beautiful species, A. mucida, varies from diaphanous white to olive 
and even black. 
Marasmius androsaceus has two varieties at least, one on oak-leaves, 
the other on pine. : 
What should we do with a Plewrotus, the spores of which show 
traces of brown or lilac-pink ? Ask those who have had to do with 
P. euosmus or P. salignus, etc. The very same thing has occurred in 
Marasmius, several species having yellow or ferruginous spores, and 
Scherffel has separated these off as a genus Phacomarasmius. Or let 
me take the group of species allied to Aygrophorus conicus, ViZ., 7. 
chlorophanus, H. pstttacinus, A. coccineus and 1. puniceus - are we 
certain of these as species, or have we here a series of prismatically 
coloured forms growing on different media and in different situations 
and varying accordingly ? . 
Or, again, let me direct your attention to that group of species and 
varieties of which Hypholoma fasciculare and H. sublateritium are the 
type. Does not H. sublateritium with its varieties Schaefferi and 
squamosum merge into Hf. fasciculare and its variety elwodes,; 7. 
capnotdes and A. efixanthum coming into the alliance? Has 
anyone worked here at the connection between form, colour, texture, 
etc., and the kind of wood and situation the fungus grows on and in ? 
{ ask, because it has appeared to me that those growing on Conifers, 
on Oak, and on other stumps seem to differ. 
Similar questions may be raised concerning Collybia velutipes and 
its allies; and an analysis of Russula, Clitocybe, and other genera and 
sub-genera afford numerous other examples. 
Need I go further in citing these mycological puzzles ? Enough 
has been said to show that any exact knowledge of the nutrition of 
Fungi must count for good in the arduous task of elucidating the 
many and perplexing vagaries of these elusive organisms. Of course, 
if we choose to push the definition of a species as merely “the unit 
in classification designating an assemblage of organisms which, in the 
judgment of any writer, is so marked and so homogeneous that it can 
be conveniently spoken of as one thing,” then it may be argued that 
there are as many species as there are opinions; but it is obvious’ 
that some consensus of opinions must be arrived at if we are to have 
species which can be conveniently accepted, and what I am advocating 
is that the accepted species must as a mere matter of convenience be 
more broadly defined—not that their variations are to be ignored or 
denied, which would be absurd. 
It does not seem likely that the more prominent morphological 
features, such as the mode of spore-formation, the arrangement of 
basidia, gills, etc., would be affected by differences in nutrition, be- 
Cause experience shows that when once the so-called morphogenic 
impulses are started, the species appears to carry them to their normal 
conclusions ; but it does appear very likely that such characters as 
texture, colour, size, excavations, compactness, viscidity, silkiness and 
numerous other minute characters known to be extremely variable 
under different conditions in other plants, may be equally incidental 
