I 
THE DEVELOPMENT OF SOME SPECIES OF AGARICS 
A, W. Blizzard 
The species of Agaricaceae whose lamellae are endogenous in their 
origin have in recent years been given considerable attention. The 
structural variation of a number of forms has been observed and 
studied. As a result a number of interesting morphological features 
have been explained and their development demonstrated. But 
very little attention has been given to those species whose lamellae 
are exogenous in their origin. It is important that the morphological 
characters of both forms be studied from their origin, beginning with 
the young, undifferentiated basidiocarp and tracing their development 
to the mature fruit body. 
Hoffmann was the first to give serious attention to the develop- 
ment of Agaricaceae. In 1856 (13) he described Panus torulosus, 
showing that the lamellae are exogenous in their origin. He observed 
the hyphae of the young basidiocarp to diverge at the apical end, and 
noted the subsequent development of the pileus. 
In i860 (14) and 1861 (15) he followed this work with a description 
of a number of forms, the greater portion having an exogenous origin 
of the lamellae. He observed the early stage of the palisade layer, 
preceding the origin of the lamellae, to be level. 
DeBary in 1859 (6) and 1866 (7) described Nyctalis asterophora, 
N. parasitica, Collybia dryophila, and others. In the main he agreed 
with Hoffmann's observations, with the exception of the condition of 
the palisade layer just previous to the development of the lamellae. 
DeBary stated that this layer was folded from the first. He later 
(8, 9) agreed with Hoffmann. 
Fayod (11) in 1889 described a number of forms. He concludes 
that the pileus primordium is endogenous in origin in all Agaricaceae. 
Since Fayod's work there are no published studies on the develop- 
ment of exogenous forms. In view of these facts, it appeared to me 
that it would be interesting to study the development of certain species 
whose lamellae are exogenous in origin. 
Material. — Basidiocarps of three species in all stages of develop- 
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