i6 
GEORGE F. ATKINSON 
Comparison with Lepiota. — It is worthy of note, however, that 
while several authors since Fries' time have stated that in Agaricus 
(Psalliota) the "universal veil" is concrete^^ with the cuticle of the 
pileus. Fries used this expression only in connection with his Tribe 
Lepiota. Studies on the development of species of Lepiota may 
throw some light on the relation of the universal veil and partial veil 
in forms where the "universal veil" is not clearly separated from the 
pileus. I have studied the early stages of development in Lepiota 
clypeolaria and find a well-formed external layer, duplex in structure 
enveloping the entire carpophore except the extreme base. This 
may well be considered a "universal veil" or the fundament of one, 
a hlematogen layer which does not become separated from the pileus. 
The portion of the partial veil lying between the margin of the young 
pileus and stem is differentiated later, and although the universal 
and partial veils never become clearly separated from each other, the 
position and structure of the universal veil is so characteristic inAhe 
young stages, that it seems reasonable from a purely morphological 
standpoint to recognize a "universal veil," or blematogen layer, and, 
in addition, a partial veil. A full account of these studies on Lepiota 
clypeolaria will be published in another paper. 
In the species of Agaricus here considered, the structure which may 
be regarded as representing the "universal veil," or blematogen layer, 
is far less distinct than it is in Lepiota clypeolaria, though clearly as 
distinct as it is in the young carpophore of Amanitopsis vaginata. 
But since there is a poorly defined external layer of the fundamental 
tissue lying outside of the more or less parallel, radiately arranged 
hyphae which organize the surface or cuticle of the pileus, though not 
clearly separated from it, we may consider this layer as homologous 
with the "universal veil," a blematogen layer in Agaricus also. As 
interpreted here it is a thin layer covering the young pileus and partial 
veil. In the very young carpophores it is rather thick and prominent 
in comparison with the fundaments of pileus and stem. As the expan- 
sion of the young plant takes place the outer portion of it is torn into 
fragments which may be so scant as to be unrecognizable, or disappears, 
or may appear as small patches on the pileus. Some of the inner 
portion may remain in close connection with the surface of the pileus, 
18 See Cooke, M. C. Handbook of British Fungi, 136, 137. Fayod, V. Ann. 
Sci. Nat. Bot. VII, 9: 1 81-41 1, pis. 6, 7. 1889. 
20Syst. Myc. 1: 19. 1821. 
