416 
Journal of Agricultural Research 
Vol. XXX, No. 5 
garded as identical with Pilacre petersii 
of Europe. He was, however, unable 
to germinate the spores of the fungus 
and so did not obtain pure cultures. 
He found, however, other fungi which 
he regarded as belonging to the Proto- 
basidiomycetes and related to Pilacre. 
One especially interesting belongs to 
the genus Pilacrella, differing from 
Pilacre in having a much looser head 
without a distinctive peridium, but 
producing prolonged branching hyphae 
all about the head. This fungus also 
produces a conidial form of hyphomyce- 
tous character entirely distinct from the 
basidiomycetous fructification. The 
conidia are sometimes borne laterally 
on the four terminal cells of the hyphae, 
suggesting somewhat in appearance the 
basidia. This led Moller to consider 
this fungus as showing a perfect transi¬ 
tion between the Hyphomycetes and 
the Basidiomycetes. Moller regarded 
Pilacre as being most closely related to 
Stypinella, a genus of Auriculariaceae. 
No recent additions have been made to 
our knowledge of Pilacre. 
Lindau (23, p. 86) places the genus 
Pilacre in the Auriculariaceae. Sac- 
cardo (32, p. 579) places it in the Stil- 
baceae of the Hypomycetes, but speaks 
of its possible relation to Roesleria 
and its lack of a typical hyphomycetous 
character. He includes 10 species, 
most of which have been described by 
Berkeley and Broome and Berkeley 
and Curtis. These are all from the 
Tropics and very little is known in 
regard to their structure or relation¬ 
ship. 
Bayliss-Elliott and Grove (11) also 
discussed the fungus and regarded it 
as probably the conidial condition of 
Roesleria. Overholts, 1922 (27, p. 
165), says he was also able to find the 
cross walls in the basidia, which are 
characteristic of the Auriculariales; 
but says that the fungus departs 
widely in consistency and habit from 
other members of the order. Lloyd 
(25) in a recent reference to the fungus 
considers it a hyphomycete. 
Beckwith (2) has pointed out that 
many authors have confused Pilacre 
with Roesleria and Coniocybe, some 
claiming that Pilacre petersii is merely 
a conidial stage of Roesleria. She 
has shown by pure cultures that Roes¬ 
leria develops only ascocarps in culture. 
As a result of the writers’ studies of 
this fungus and those cited bearing on 
this and other fungi which are more or 
less related to it, they are of the opinion 
that it represents what might be ap¬ 
propriately called a protogasteromy- 
cete. Its nearest known relative at 
present among the Gasteromycetes is 
apparently Tulostoma, as suggested by 
Schroeter (33) . It is not unlikely that 
when the fungi of the world are more 
fully known other genera will be found 
partially bridging the gap between 
genera like Pilacre and Tulostoma. 
As already indicated, Brefeld and 
Moller showed that Pilacre faginea 
possesses true basidia, and on account 
of these being transversely septate and 
bearing lateral spores regarded it as 
more closely related to the Auricu¬ 
lariales than to the Gasteromycetes. 
Brefeld (5, p. 194) at first, basing his 
opinion on Tulasne’s account of Pil¬ 
acre, stated that the Gasteromycetes 
had most probably arisen from a simi¬ 
lar form. Schroeter pointed out its 
angiocarpous character and the re¬ 
semblance of the basidia and spore 
formation to that of Tulostoma. 
Eidam (10) has shown the presence 
of clamp connections in Cyathus and 
Crucibulum, while so far as the writers 
know at present, these have not been 
found in the Auriculariales. This 
would also appear to indicate the 
closer relationship of Pilacre to the 
Gasteromycetes than to the Auriculari¬ 
ales. 
SUMMARY 
The life history of Pilacre faginea as 
determined by Brefeld has been verified 
by pure cultures from basidiospores and 
also from conidia, the perfect or bas¬ 
idiomycetous stage being produced in 
both cases. It is shown that this fungus 
has true basidia, each arising from a 
clamp connection, which is a two-nu¬ 
cleate structure. These nuclei fuse and 
undergo two divisions so that the ma¬ 
ture basidium consists of four uninu¬ 
cleate cells. 
The fungus is shown to possess two 
distinct stages of development, the 
gametophytic and sporophytic, dif¬ 
fering in the color and character of the 
mycelium and in the character an(. 
method of production of the spores. 
The conidial stage (gametophytic) has 
the general appearance of a hyphomy¬ 
cete similar to Rhinotrichum or Hap- 
laria. The basidial stage (sporophytic) 
has the general characteristics of a 
Basidiomycete, having clamp connec¬ 
tions and uniformly four-spored basidia. 
The sporophytic stage produces a 
distinct more or less stipitate sporocarp 
having a gleba and peridium suggestive 
of a Gasteromycete. Brefeld and Mol¬ 
ler, who made careful studies of the 
fungus, regarded it as intermediate 
between the Auriculariales and Gaster¬ 
omycetes. Schroeter regarded it as 
having closer affinities with the Gaster¬ 
omycetes. 
The evidence accumulated by the 
writers leads them to regard this fungus 
