1212 Wisconsin Academy of Sciences, Arts, and Letters. 
The hypertrophied petioles were full of smut halls in all 
stages of development. This is one of the forms of smut halls 
in which the fertile cells are on the outside and the sterile cells 
form a pseudoparenchyma in the interior; the exact reverse of 
the conditions in D. Alismatis. Setchell (38) has described 
the morphology of the smut halls of this species very thoroughly. 
The hall begins as a tangled mass of hyphae in one of the in¬ 
tercellular spaces of the hypertrophied host tissue (Fig. 40). 
It is not possible to make very much out of the nuclear struc¬ 
tures at this time as the cytoplasm is very dense. Careful 
staining, however, with the iron-haematoxylin will bring out the 
fact that many of these cells are binucleated; whether all are so 
is difficult to say. I should say from my preparations that the 
binucleated condition is probably constant, for while in some 
cases the cytoplasm is too dense for the nuclei to be seen, in all 
cases where they can be seen there are always two and only two 
present. 
At the beginning, the cells are all alike, but those on the in¬ 
terior soon begin to lose their contents and become transparent 
(Fig. 41). The material in the cell seems to all go to in¬ 
crease the size of the cell. The outer cells remain dark-staining 
and apparently furnish new cells to the central region as the 
original number of cells there is not a fourth of that which is 
found in the mature balls and I do not believe that these central 
cells divide. It may be possible that the hyphae from the onit- 
side push in between the fertile cells on the outside and add fur¬ 
ther pseudoparenchymatous cells to the interior and there seems 
to be some indication that this occurs. In the last stage, that of 
the nearly mature spore-ball, the external cells are dense with 
cytoplasm and contain two nuclei that are in various stages of 
fusion. Surrounding these are the protective hyphae, wound 
around the exterior of the ball, making a. felted layer outside it 
(Fig. 42). 
The nuclei of the cells of the mycelium are rather difficult to 
differentiate out but in the felted layer around the spore mass 
two nuclei are usually found associated together. In the long 
hyphae, also, that run across the intercellular spaces an ar¬ 
rangement of the nuclei in pairs seems to be the rule in the cells. 
