HoGG^ on Parasitic Fungi. 
55 
of late years on plants have been caused by a peculiar at- 
mospheric condition not yet perhaps quite understood^ but 
which, when combined with want of vigour, or, in other 
words, unhealthy growth, arising from the loss of some che- 
mical element in the soil necessary to health, has been pro- 
ductive of the various ''murrains^' of which we have heard so 
much. A fact well known to microscopists is, that, during 
heavy, moist, and other unpleasant atmospheric conditions, 
the spores of various fungi can be caught by merely exposing 
a slip of glass in a current of air — but when the atmosphere 
is fine and dry, a state usually recognised as bracing and 
favorable to health and life, fungi and their spores are very 
difficult to collect, and probably are not then floating about. 
Similar causes may, doubtless, affect the microscopic cha- 
racters of the products found in skin diseases, and so similar 
in appearance are the fungi taken in the air to those found 
among plants and decaying vegetable matter, that with a 
power of two or three hundred diameters we detect a striking 
analogy between them. The Achorion Schoenleinii in par- 
ticular, and many of the vegetable moulds, recognised under 
the generic terms of Penicillum and Aspergillus, very closely 
resemble each other, in fact are forms of the same family of 
fungi. The botanical characters of the Penicillum, one of 
the most common of the fungi, forming and spreading itself 
as a greenish mould on decaying vegetable substances of all 
kinds, may be summed up in a few words : it simply consists 
of a mycelium of interwoven filaments, articulated and ter- 
minating in a plume-like head of minute globular spores, 
yellowish or bluish in colour, according to age. 
The Aspergillus of Greville differs only in some slightly 
peculiar form of its spores, which are ovoid, and are borne 
on erect filaments, terminating in irregular tufts. 
If the spores of either are sown on a glass slide and kept 
slightly moist, they quickly germinate, and their similarity 
will be readily perceived. 
On living plants they are more familiarly recognised by 
such names as smut, brand, bunt, &c. 
Table VII represents some well-executed drawings of 
those referred to, also an Alga found growing in distilled 
water, and the most common forms of fungi met with caught 
in the air. Upon examination, every person must be struck 
with the remarkable family resemblance. Even the mush- 
room spores differ in size only, as a comparison must prove ; 
all the latter figures having been drawn under magnifying 
power of 200 diameters. 
The Muscardine is due to a species of fungus like 
that which infests the potato, the sporules of which are 
