1 86 STRICKLAND: NOTES ON FUNGI. 



we have in them a group of organisms which, being parasitic upon 

 comparatively recent highly-developed phanerogams, must themselves 

 be comparatively recent species, and consequently specially liable to 

 variation. This fact of their very general parasitism, and their great 

 variety of forms, leads me to look at the difficulty of identification 

 of the species from yet another point of view. What part has the 

 host to play in the creation of a new species ? The answer to this 

 question is one of very general interest, for we are all parasites of the 

 earth we live on. Let us take as examples two typical highly-evolved 

 parasitic fungi. Everyone knows the common autumn toadstool, 

 which grows so abundantly on all sorts of rotting stumps close to the 

 ground, or on logs of wood half-buried underneath it, scientifically 

 known as Agaricus {Armillaria) melleus. It has a dirty-honey-coloured, 

 somewhat scaly pileus; it is gregarious; has a stringy, straight stem, with 

 a dingy ring; and seems to flourish indiscriminately on all sorts of hosts. 

 It is a general and very common type. Now let us turn to its near 

 relation (own brother, I might say), a fungus, however, of much more 

 elaborate form and of much rarer occurrence, the beautiful Agaricus 

 {Armillaria) mucidus, one of the most wonderful of our native agarics. 

 No one who has once seen it can fail to recognise the slender, dove- 

 coloured, satiny stem, with its grey, ruffle-like ring, dusted above with 

 the mealy- white spores ; the ivory-like gills, rounded and wide apart ; 

 and the dome-like, semi-transparent porcelain pileus, of a colour 

 between umber and sepia, clothed with its shining glutinous coat. 

 Now, this much less common, much more specialised, fungus is 

 almost invariably parasitic upon beech trees ; it is, therefore, difficult 

 to avoid a suspicion that it is the descendant of some Armillaria of 

 more catholic tastes, like the extremely common A. melleus, which 

 flourished, possibly before beech trees were, indiscriminately upon 

 various decaying trees, and whose spores afterwards settled on the 

 decaying branches of beech trees, there throve, and there evolved 

 another form. I believe it is eaten by Squirrels, but still it is difficult 

 to believe that the beautiful form of the plant has been evolved 

 through its greater attractiveness to these animals and to the eyeless 

 grubs and worms which also feed upon it. There seems to be some 

 connection between the fall of the sap in trees and the appearance 

 of certain forms of fungi. Thus the unmistakable Agaricus (Pholiota) 

 squarrosus appears at the foot of ash trees past their prime, just 

 as the sap sinks down in autumn. Is, then, the beautiful form 

 of Agaricus (Armillaria) tnucidus due to the quality of the sap 

 and juices of its host ? So that the beautiful form is a by-product or 

 side manifestation, so to say, of the general health, vigour, and 

 symmetry produced by the new blood poured into its veins from its 



Naturalist, 



