48 
THE CLASSIFICATION OF DISCOM YCETES. 
this group the asci do not open, but disappear insensibly 
by absorption, and thus leave their sporidia free. This group, 
altogether natural and distinct, certainly belongs to theAscomycetes, 
but should not be placed in the Discomycetes, from which they 
differ notably. I may say the same of the Pyrenomycetes in which 
the greater part of the species probably have dehiscent asci, but 
this family, in which the processes are most difficult to observe, 
does not come within the limits to which I confine myself. 
It will be seen from what I have said, how much importance I 
attach to the mode of dehiscence, and it is with the view of induc- 
ing mycologists to observe it more carefully that I have dwelt upon 
it. There is no great difficulty in observing it, a magnifying power 
of 300 diameters is sufficient, but it is necessary to search for it at 
the upper extremity of the open asci. These asci are always to 
be recognised by the absence of protoplasm, by which they differ 
from the young plants which have not yet formed their sporidia. 
Moreover, the tincture of iodine may be employed, which colours 
the membrane and renders the operculum more visible. This tinc- 
ture should, indeed, always be employed in the examination of 
species, because it often gives a deep blue colour at the extremity 
of the ascus, as in Aleuria proper, P. cochleata , P. badia , 
P. vesiculosa , and others, and the character has a certain value ; in 
other cases the colour is fainter, as in P. firma. P. echinophila , &c.; 
in other cases again, only the extreme margin of the opening is 
tinted, as in Mitrula , or it appears as a blue point, while more fre- 
quently the iodine does not produce any other colouration than a 
yellowish tint to be produced. 
I believe these observations are of great use in the natural classi- 
fication of the numerous species of this difficult family, upon which the 
efforts of the most able mycologists have been more and more 
engaged of late. I believe, too, it may prevent other less happy 
arrangements. I will mention for example Peziza tuberosa and 
P. rapulum , which have their asci inoperculate, placed by Persoon 
and by Fries, and even by modern authors, amongst the Aleuria , 
in which these organs are operculate. Nevertheless these species 
have something in their aspect nearly approaching Phialea, as 
Persoon in his Synopsis (p. 644) had already remarked “ de 
intuitu ” of P. tuberosa. 
The Lachnea , Humaria, and other genera beside with operculate 
asci, contain many species which ought to be withdrawn and placed 
in the second division. 
It is only by examining the species in a fresh state that any perfec- 
tion can be attained in a study so difficult as the classification of 
Pezizce. In the dry state these observations are very difficult and 
often impossible, in consequence of the contracted condition in 
which the asci are found. 
These two sections in the Discomycetes form two parallel series 
agreeing well in the base. Thus the Operculce commence with the 
