CLUSTER-CUPS. 
21 
botanical descriptions. Useful and essential as they may be, 
we hope to be enabled to furnish something more ; and 
although we at once disclaim any intention of including all 
the microscopic, or even the epiphytal fungi, in our observa- 
tions, yet we trust, by a selection of common and typical 
species for illustration, to demonstrate that the microscopist 
will find an eligible field for his observations in this direction, 
and the botanical student may gain some knowledge of their 
generic distinctions. 
It is exceedingly difficult to give a logical definition of what 
constitutes a fungus. It is no less difficult to furnish a popular 
description which shall include all and nothing more. If, for 
example, we particularize the spots and markings on the leaves 
and stems of herbaceous plants so commonly met with from 
early spring till the fall of the last leaf, and even amongst the 
dead and decaying remains of the vegetation of the year, we 
may include also such spots and marks as result from insect 
depredations or diseased tissue. It is not always easy, with 
a cursory observation under the microscope, to determine 
whether some appearances are produced by fungi, insects, or 
organic disease : experience is the safest guide, and until we 
acquire that we shall occasionally fail. 
If we take a stroll away from the busy haunts of men, 
though only for a short distance, — say, for example (if from 
London), down to New Cross, and along the slopes of the 
railway cutting, — we shall be sure to find the plant called the 
goatsbeard in profusion. In May or June the leaves and 
unopened involucres of this plant will present a singular 
appearance, as if sprinkled with gold-dust, or rather, being 
deficient in lustre, seeming as though some fairy folk had 
scattered over them a shower of orange- coloured chrome or 
turmeric powder. Examine this singular phenomenon more 
closely, and the poetry about the pixies all vanishes ; for the 
orange powder will be seen to have issued from the plant 
itself. A pocket lens or a Codrington reveals the secret of 
the mysterious dust. Hundreds of small orifices like little 
yellow cups, with a fringe of white teeth around their margins, 
will be seen thickly scattered over the under-surface of the 
leaves. These cups (called peridia) will appear to have burst 
through the epidermis of the leaf and elevated themselves 
above its surface, with the lower portion attached to the 
substratum beneath. In the interior of these cup-like ex- 
crescences or peridia , a quantity of the orange- coloured, 
sphoerical dust remains, whilst much of it has been shed and 
dispersed over the unoccupied portions of the leaves, the 
stems, and probably on the leaves of the grass or other plants 
growing in its immediate vicinity. These little cups are fungi, 
