Lutmun—Life History and Cytology of the Smuts. 1207 
Ustilago Zeae (Beckm.) Ung. 
Pure cultures of the conidia of this smut were obtained by 
plating out the spores on 1 % beer-wort agar. A transfer was 
then made to flasks of liquid beer-wort. When a thick white 
sediment of conidia had collected in the bottom of the flask the 
culture was shaken up and sprayed into young corn ears in 
which the silk had just appeared as recommended by Brefeld 
(5). After a week or ten days the young kernels were found 
hypertrophied usually on one side or one end. These affected 
parts were fixed in Flemming’s Weaker Solution. Sections of 
such a part would show an abundance of smut hyphae between 
the cells. The very early stages when the smut was making its 
way into the ear could not be obtained in this way but all later 
stages up to and including spore formation were abundant. 
The appearance of the mycelium (Fig. 18) in these hyper¬ 
trophied parts of a kernel is practically the same as that of the 
mycelium of U. levis in the oat plant. It is largely intercellu¬ 
lar, much twisted and branched, and the cells are multinucle- 
ated. The host cells are apparently in a fairly healthy condi¬ 
tion but somewhat hypertrophied. 
The process of spore formation is essentially similar to that in 
IT. levis. De Bary (14) and Miss Knowles (26) have des¬ 
cribed the external features of it very accurately. The blunt 
and much branched ends of the hyphae form balls which fill the 
intercellular spaces between the host cells. There is great vari¬ 
ation in the size and shape of these hyphal ends but they are al¬ 
ways multinucleated. The same gelatinization of the hyphal 
walls occurs, making it impossible to distinguish anything ac¬ 
curately in the hyphae at just this stage. Some of the segments 
show, when stained with iron-haematoxylin, two dark staining 
bodies that are undoubtedly the nuclei. The segments (Fig. 
19) at this time may be irregular or only long, but they all have 
very thick walls. A little later (Fig. 20) when these segments 
have changed their shape and become spherical, it is easier to 
distinguish the nuclei. Some of them show two but there are 
others with apparently only one. The same thing that was said 
of TJ. levis applies here; it is impossible to prove whether a 
