BUSTS. 
333 
widely- diffused plant, tlie wood cow-wheat [Melampyrum 
pratense), known well to all amateur botanists for its per- 
tinacity in drying black, and presenting anything but an 
inviting appearance to claim for it a place in the herbarium — 
also becomes the matrix for the development of a member of 
this genus ; i. e. the cow-wheat rust ( Goleosporium Rhinan- 
thacearum , Lev.), and which is found on other allied plants, 
as the little eyebright [Euphrasia officinalis ), &c. (Plate XII. 
fig. 24). In colour and habit it resembles the last-named 
species, and its free, echinulate spores (Plate XII. fig. 25) 
form a pretty object for the microscope. 
Another equally common species is found inhabiting the 
leaves of the sow-thistles ( Sonchus arvensis and S. oleraceus), 
and in the autumn may generally be found on either of those 
plants, presenting the appearance delineated in our plate 
(Plate XIII. fig. 26). The permanent spores resemble in many 
points those of the first species, as will be seen from the figure 
from De Bary’s treatise on this subject (Plate XII. fig. 27). 
This is certainly one of the. most showy of uredinous fungi, 
and could not be well overlooked. 
The butter-bur rust [Goleosporium petasites , Lev.) and the 
Campanula rust [Goleosporium Campanulas, Lev.) are found, 
the former on the leaves of the butter-bur, and the latter on 
those of the harebell and other Campanulas, less frequently. 
We have, however, indicated sufficient, since their great 
similarity in unprofessional eyes will furnish, in one or two 
species, all that is desirable for the microscopist. 
Unless a similar plan be adopted for examining the species 
of this genus to that recommended for the white rust, it may 
result in disappointment; for the slight attachment of the 
joints to each other will otherwise present only a mass of 
simple echinulate cellules, if a portion be only removed from 
the leaf on the point of a lancet. Any person possessed of 
the cardinal virtues of microscopy — patience and perseverance 
— will be rewarded in this instance; whilst those who are 
deficient will lose an object worthy of the virtues they dare 
not boast. But few instances have occurred in this and the 
preceding papers in which the exercise of any great ingenuity 
or application has been called for ; the most juvenile or truest 
tyro at the microscope may see for themselves much of what 
has been indicated, whilst a few opportunities have occurred 
for more practised manipulists to prove that they are neither 
juveniles nor tyros. 
It can scarcely be too great an assumption to suppose that 
every one is acquainted with the goat- willow [Salix caprcea), 
or that every schoolboy knows the birch [Betula alba). It 
may be proceeding a step too far to affirm that all who know 
