480 
Journal of Agricultural Research voi. xxvn, No. 7 
Lutman (28) studied the nuclear condition of the mycelium and 
nuclear phenomena at the time of spore formation in a number of smut 
fungi belonging to the Ustilaginaceae and to the Tilletiaceae. He states 
that in the Ustilaginaceae the mycelium is characteristically multinu- 
cleate, whereas the mycelium of the Tilletiaceae frequently contains 
binucleate cells. In the latter family, Entyloma nymphaeae (Cunn.) Set. 
had binucleated cells and this condition also was characteristic of the 
older mycelium of Urocystis anemones (Pers.) Wint., Doassansia alis - 
mails (Nees) Cornu., and D. deformans (Setch.). Paravicini (36) studied 
certain members of this family and observed that the sporidia conju¬ 
gated in pairs, with or without the intervention of a fusion canal, and 
that a nucleus wandered from one sporidium to the other and thus estab¬ 
lished a binucleate condition. In U. anemones , fusions were seen only 
rarely, and in U . violae } where he observed binucleate sporidia with a 
fusion canal between them, he was of the opinion that nuclear migration 
occurred between sporidia also. He states that in both families of the 
Ustilaginales the binucleate condition arises through conjugation of the 
sporidia or hyphal cells and is maintained until the spores are formed. 
He states that when the spores of Urocystis anemones germinated, 
sporidia were not formed, but he describes the appearance of easily 
detached mycelial threads which at first contain a single nucleus. Con¬ 
jugation of these bodies was not observed, but they became septate, 
each cell contained a single nucleus, and finally certain of these cells 
became binucleate as a result of the migration of a nucleus from an 
adjoining cell. He draws an analogy between these mycelial threads and 
the promycelium of such forms as Ustilago tritici and U. nuda } 
although a phylogenetic relationship is not suggested. Paravicini has 
stressed the fact that conjugation of sporidia is of common occurrence 
and considerable significance in the sexuality of the smuts. 
Uutman (28), however, has stated that “it is probable that the para¬ 
sitic mycelium rarely or never starts from the conjugated conidia or 
promycelial cells even though they represent the old method of repro¬ 
duction.” 
NUCLEAR PHENOMENA AT SPORE GERMINATION 
The nuclear phenomena of the germinating spores of Urocystis tritici 
or of U . occulta apparently have not been studied. There are some 
marked morphologic resemblances between the promycelia and 
sporidia in these forms and the homologous structures produced by 
such forms as U. anemones y U. filipendulae , and others mentioned 
above, but the nuclear phenomena involved at germination appear to 
differ from those which have been described for such forms by Paravicini. 
The writer has made an extensive study of the general characters of the 
nuclear phenomena associated with the germination of spores of Urocystis 
tritici . Spores in different stages of germination were fixed in Flemming's 
weaker solution for periods up to two hours, transferred to several 
changes of water, and then to slides coated with egg albumen. The 
transfers were made with a platinum loop, this procedure being more 
satisfactory than direct fixation of the spores on the slide. When the 
slides were almost dry, a drop of 80 per cent alcohol was added as in the 
method described by Harper (13), and the slides were passed through the 
regular series of alcohols and then stained. Several staining methods 
