AMERICAN 
JOURNAL OF BOTANY 
Vol, V October, 191 8 No, 8 
THE CYTOLOGY OF EOCRONARTIUM MUSCICOLA 
Harry M. Fitzpatrick 
The view of Brefeld (5) that the promycehum of the Uredinales 
and Ustilaginales is homologous with the transversely septate basidium 
of the Auriculariales has received general acceptance. His theory, 
based on a morphological study of the two structures, has been sub- 
stantiated by the results of subsequent cytological investigations on 
members of these three groups and of the higher Basidiomycetes. 
Consequently the Auriculariales are regarded as closely related to the 
Uredinales, and as probably intermediate in origin between them and 
the higher Hymenomycetes. Comparatively little is known, however, 
concerning the nuclear history and general cytology of members of 
this order. Only species of the genus Auricularia have been examined, 
and here the facts are only partially determined. The investigation of 
members of other genera is therefore desirable, and should shed further 
light on the phylogeny of the Basidiomycetes. 
A preliminary examination of stained sections of the sporophore of 
Eocronartitim muscicola (Fries) Fitzpatrick, made in connection with 
the writer's (12) study of the parasitism of this species, disclosed the 
fact that unusually large nuclei make this form a favorable subject 
for cytological investigation. The present paper is an outgrowth of 
this discovery, and embodies the results of an investigation of the 
cytology of this species conducted during the past three years. 
Materials and Methods 
Eocronartium muscicola is an obligate parasite occurring on a 
considerable number of mosses of various genera. It produces small 
Typhula-like sporophores at the apices of the branches of the moss 
gametophore, in which it exists as a perennial, intracellular parasite. 
[The Journal for July (5: 337-396) was issued Aug. 3, 1918.] 
397 
