1206 Wisconsin Academy of Sciences, Arts, and Letters. 
The cell walls of the hyphae now begin to gelatinize from the 
inside (Fig. 14), a clear zone appearing between the protoplasm 
and the darker staining wall. The nests or pustules of hyphae 
continue to grow and swell and their walls become so completely 
gelatinized at this stage (Fig. 15) that all that seems to be pres¬ 
ent is a tangle of hyphae of irregular shape and varying di¬ 
ameter without walls and lying in a clear matrix. At the same 
time the walls of the host cells immediately adjacent lose the ca¬ 
pacity to take up the stain, the gelatinization of the fungal walls 
having apparently extended to the walls of the host cells also. 
The gelatinized walls do not stain at all in the iron haema- 
toxylin and only take a faint blue in the triple so that all that 
appears in the sections are the darker staining protoplasts of the 
hyphae. The protoplasm of the latter seems to be so dense at 
this time that it is almost impossible to distinguish nuclei. 
Bodies appear in them which may be nuclei (Fig. ,1'6) but it is 
impossible to say with great certainty. The hyphae continue 
to spin out more and more becoming still more finely attenuated 
in places until they are apparently pinched off into segments 
(Fig. 17). At this time these little pieces of hyphae are very 
angular and the walls difficult to make out. Some of these little 
pieces show two nuclei and some one. Whether the two fuse to 
form the one cannot be ascertained with certainty as they are ex¬ 
ceedingly small and about all that can be said about them is that 
they sometimes contain two dark staining bodies and sometimes 
one. The irregular segments now change their shape, round up, 
and the spore wall begins to develop. 
From this account it will be seen that the uninucleated con- 
idia of U. levis frequently become multinucleated before they 
cause infection. The mycelium is composed of multinucleated 
cells from its beginning and these are continued throughout the 
life of the fungus up to the time of spore formation. At that 
stage the hyphae break up into segments, the number of nuclei 
of which is difficult to determine, but which is either one or two. 
The young spores contain one or two nuclei and the mature ones, 
one, but it is not possible to determine with certainty whether at 
some early stage all have two which later fuse to form the single 
one. 
