1202 Wisconsin Academy of Sciences, Arts, and Letters. 
house apparently retarded and stunted the growth of the young 
oat plants so much that the fungus was able, In most cases, to 
keep pace with it and it was only the most rapidly growing indi¬ 
viduals that were able to push ahead of it. When the plants 
were given a fairer chance under more normal conditions, as in 
the spring months, a larger number could outgrow the fungus 
and produce clean heads. 
There has been considerable question as to whether U. levis 
is a true species or whether its characters of smooth walled 
spores, formed in rather definite pustules, are only the result of 
physiological conditions in the host plant, leading to these char¬ 
acteristics in the parasite. In the course of these experiments 
I have carried this smut through three generations and have al¬ 
ways had the same kind of heads in which the smut is enclosed 
in the only partly destroyed glumes and the same smooth walled 
spores. It may be that my conditions were the very ones re¬ 
quired to bring out these peculiarities but it would hardly seem 
that they would appear for three successive times and in plants 
grown both rapidly and slowly. So I am inclined to regard 
IJstilago levis as a stable species. 
My principal object in the above experiments was to obtain 
an abundance of the fungus at all stages of its development for 
further study of the cell structure, spore formation, etc. 
For the younger stages of the mycelium the parts of the leaf 
sheathe under the smear of conidia were sliced off and fixed in 
Fleming’s weaker solution. For the older stages when the 
growing point of the plant had become infected (10 days-2 
months) the older leaves were removed and the entire growing 
tip fixed, usually also in Fleming’s weaker solution. Staining 
was largely with the triple stain although the iron-haematoxylin 
was also used. 
In addition to the parasitic stages of the fungus it was possi¬ 
ble also, from the cultures to get all stages in its Saprophytic de¬ 
velopment. The conidia, as has been frequently described be¬ 
fore, reproduce abundantly by budding in the same manner as 
yeasts. Ordinarily the bud drops off almost as soon as formed 
but in rich media, long chains of these, produced by continued 
budding without separation of the cells may remain together. 
