290 DIVISION II-—COURSE OF DEVELOPMENT OF FUNGI. 
adopted. The veil is rent by the upward extension of the pileus, and often, but not 
always, in such a manner that a portion of it remains behind on the stipe as an 
annular frill (ring or annulus). 
The veil appears in two principal forms; first, as a membrane running from 
the margin of the pileus to the surface of the stipe, and therefore does not enclose 
much more than the hymenial surfaces, but leaves all the other part free; in this case 
it may be called a marginal veil, or with Fries velum partiale (Fig. 132). Secondly, 
as a sac which encloses the entire sporophore from its base, and is ruptured at the 
apex by the unfolding pileus; in this state it is the velum universale or volva (see 
below, Fig. 135). 
1. As regards the development of the forms which have the marginal veil 
only the following special facts have been established by observation. Up to the first 
formation of the pileus on the summit of the stipe-primordium the phenomena are the 
same in essential points as in the gymnocarpous forms (Fig. 24 a). The young 
pileus is entirely delimited from the stipe by 
a transverse annular furrow running along 
its future hymenial surface. But then the 
superficial hyphal layers of the stipe and 
of the young pileus send out numerous 
branches towards one another from the 
edges of the furrow; these unite into a 
close weft, the marginal veil, which bridges 






es 
FS 
era 
Ira 
Ina 
a 

oe 
=. 
Fe 

N 
ae over the furrow and closes it on the outside 
Ina, (Fig. 133). The body of the pileus then 
N N developes from the inner hyphal layers of 
the primordium, those which are nearest the 
furrow, and chiefly by uniform growth in 
FIG. 133. Agaricus melleus. Half of a thin median longitu- the direction of the margin and by alternate 
dinal section through a young pileus before the closing of the a Pr 7 . 
veil; # the annular furrow between the pileus and the stipe epinastic and hyponastic growth, as in 
bounded above by the of the h i else- 5 . a . 
where by the veil which has begun to develope. After R. the species which have no veil. The veil, 
Hartig, Wichtige Krankh. d. Waldbäume, t. II. Magnified. r A . 
together with the portion of the stipe in- 
closed by it, follows the superficial increase 
in size of the pileus by intercalary growth, till the hyponastic expansion of the latter 
commences. 
The veil therefore in these cases is, as Bonorden described it, a continuation of 
the outermost row of cells of the stipe, which grows with the stipe for some time by 
intercalary growth and passes into the margin of the pileus, and conversely a 
continuation of the outermost hyphae of the pileus passing into the surface of the 
stipe; it is composed in fact of hyphae of this twofold origin. The structure is 
differently formed in each separate case, the difference depending on whether it 
begins to be formed in a somewhat later or earlier stage of the development, and in 
connection with this whether the hyphae which take part in its formation and run 
downwards from the pileus have their origin at a greater or less distance from the 
centre of the pileus, while those which run upwards from the stipe reach more or less 
of the way to the apex of the pileus; and also on whether the margin and hymenial 
projections of the pileus are closely applied to the stipe or are more or less distant 

