Distribution of Fungi. 283 
Lund, entitled ‘Conspectus Hymenomycetum circa Holmiam 
crescentium.’ 
In botanical geography, great importance is attached to the 
differences prevailing among plants in relation to their distribu- 
tion, according as they are diffused, isolated, or numerous in the 
localities they inhabit. These differences are, in the case of the 
Fungi, even more manifest than among the Phanerogamia : 
there are species of Fungi of which isolated individuals only are 
‘to be found; others always met with in groups of larger or 
smaller numbers; and others, again, which constantly grow in 
dense clusters or aggregations. Among those species of the 
second variety named which are collected in social groupings, 
the aggregation is frequently the result of all the individuals 
springing from a common mycelium. Sometimes such collec- 
tions form in extended circles or in long lines, according to the 
mode of development of the mycelium, which at times expands 
itself in a centrifugal manner, or circularly, and developes the 
Fungi at its periphery, and at others elongates itself only in one 
direction. The Merulius lacrymans (the common Fungus of the 
house) grows in a circular fashion, and attracts moisture from 
the atmosphere, which it afterwards exudes from its periphery 
in the form of aqueous drops: by this property it hastens the 
progress of decay of the wood, which is a necessary condition to 
its development. In hot countries a no less curious form of 
mycelium is observable, consisting of a filamentous mucilage, to 
which particles of earth, small stones, and other fragments of 
matters it encounters in its expansion become so agglutinated as 
to constitute a sort of conglomerate, which, on being dried, 
assumes a hardness equal to that of stone itself. In this manner 
the pietra fungaja of Italy is formed by the mycelium of Poly- 
porus tuberaster ; in tropical countries, some similar productions 
are due to the mycelium of certain species of Lentinus. 
The stations of Gasteromycetes are generally the same as those 
of Hymenomycetes. The Phallodei and the Hymenogastrei, 
which are the most important groups of Gasteromycetes, all 
grow upon the ground—are geogenous. The Nidulariacei and 
the Lycoperdacei are partly geogenous and in part epiphytes. 
Among the Trichodermacei are the two singular genera Aste7o- 
phora and Onygena, the former of which is parasitic on other 
Fungi, whilst the most remarkable species of the latter live on 
animai refuse ; thus Onygena equina has its special habitat on 
the hoofs of the horse, and the O. piligena on the hair and skin 
of dead Mammalia. 
The other families of Fungi exhibit in regard to habitats 
(stations) many remarkable examples. The species of the sub- 
genus Hypomyce, belonging to Hypocrea, form a lining to the 
