130 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
are shown by all the imperfect spores of these two groups; this char¬ 
acter is very clearly defined in the genus Tremella, where the ger¬ 
minating basidiospores produce abundant bud cells. The conidia 
and bud cells may immediately reproduce themselves by sprouting 
or they may produce normal mycelia and basidiosporic fructifications. 
Although these imperfect spores are probably normal and important 
factors in the reproduction of the Auriculariineae and Tremellineae, 
they are by no means so highly differentiated morphologically as are 
the spores of the Uredineae, nor is the life history in these groups 
complicated by the regular succession of spore forms commonly seen 
in the rusts. 
In Pilacre petersii B. & C., Brefeld (’88) found, in addition to 
four-spored basidia of the Auricularia type, numerous non-septate 
conidiophores resembling the basidia in form, but bearing many 
spores. On account of the similarity between these two organs, 
Brefeld believes that the basidium of Pilacre has arisen from the 
conidiophore by the development of septa, and by the reduction of 
the spores to the fixed number four, and that this genus marks one of 
the several points of origin of the Basidiomycetes from the Hypho- 
mycetes. Moller (’95) found a fungus in Brazil which is similar to 
the European Pilacre petersii but produces no conidia. He also 
describes from Brazil a new species of Pilacrella, a genus which bears 
some resemblance to Pilacre. This species produces conidiophores 
which show all gradations into normal basidia, and bear conidia 
which are indistinguishable from the basidiospores; in addition to 
these large conidia, small spermatium-like cells are abjointed from the 
ends of certain hyphae. 
It is not certain where the genus Pilacre should be classified, and 
the position of Pilacrella seems still more uncertain. Saccardo 
(“Sylloge fungorum,” vol. 4) places Pilacre among the Stilbeae of 
the Hyphomycetes, while Boudier (’88b), finding indications of ascus 
formation, classes a number of the species under the Discomycetes. 
Brefeld (’88), Lindau (’00), and Patouillard (’00) place the genus 
under the Protobasidiomycetes near Auricularia. This classification 
is supported by Istvanfh (’95) who says: ‘‘The young basidium of 
Pilacre petersii has a nucleus which later divides into four daughter 
nuclei that migrate into the young spores.’’ Further study of this 
organ is necessary before its character is clearly understood, and before 
the basidiomycetous nature of Pilacre is definitely proven. 
