4, Were Sonar ~~) tH ? ath na eh ¥ 
an A es "ane ‘ > a ic Say na ie ae, 
WN ie Peg alee Le Ma eh tia Rea oe RN cag eh eo ee ‘ 
882 «—- REPORT OF THE COMMISSIONER OF AGRICULTURE, 
The stem sometimes bears spore masses ¢ 
the surface of the ground, as stated by Kiihn, 
as observed also by the writer. From this ] 
to the tips of the tassel they may occur at almost ~ 
any point. The ear is oftenest affected, especi-— 
ally the grains of corn upon the ear (Plate Str, 
Fig. 1). It is rare that all the grains are af-— 
fected at once; there are almost always some _ 
good ones. The bracts at the base of the ovaries — 
or young grains become greatly distorted (Plate — 
XIII, Figs. 1-14), and the husks inclosing the ear ~ 
much more so. "When the smut forms a ring 
around the middle of the ear the grains above 
are often aborted (Plate XIII, Fig. 1). In the- 
staminate flowers (tassel) the swellings are not so — 
large. The presence of the fungus does or some- _ 
times does not prevent the formation of pollen, — 
Seach EUR ata and the swelling which precedes the appearance — 
(tassel) infested by smut Of the powdery mass is not usually formed till 
(after Peck). after the pollen ripens. | vi oa 
Less frequent, but by no means rare, are the spore masses in stems, 
leaves, and sheaths. Those on stems (Plate XII, b) often havea con-~_ 
siderable size, but upon leaves especially they are smaller and less — 
luxuriant in appearance, sometimes no larger than a pea. wees 
The form of the swellings is in general rounded oblong, but usually — 
broader at the free end and narrowed at the point of attachment, e 
They are covered by a whitish or lead-colored membrane, tightly — 
stretched at first, but later becoming wrinkled and bursting to alow — 
the escape of a mass of powdery spores (Plate XIII, Fig. 13). Ifa — 
swelling is eut open when young it appears slimy and spongy; in ~ 
color uniformly whitish. An older one will be found to contain — 
certain blackish spots or stripes (Plate XIII, Figs. 3,8, and 14),andat — 
_ length the whole mass becomes blackish-brown. At this stage the — 
membrane bursts and the spores are blown away. 
. '. 
(c) THE FUNGUS. oa 
The fungus is found within the corn plant when the latter is quite 
young, and during the vegetative period, up to the time when spore ~ 
formation takes place it consists only of mycelium. This necessa--~ 
Pa 
rily begins its growth near the surface of the ground, since it enters. _ 
when the corn is very young, and as the latter grows in height _ 
the mycelium also grows upward toward the place where it is after- 
ward to form its spores. It lies mostly parallel to the part in which ~ 
it is growing, and in soft tissues extends as a uniform thread fora 
distance equal to the diameters of several plant cells; but at intervals, 
especially where the cell walls are firmer, branching takes place _ 
(Plate XIV, Figs. 1 and 2), and a plexus of filaments is frequently 
formed, as are also haustoria or suckers, the special organs for ab- — 
sorbing nutriment. These are most abundant in the leaves. The — 
thicker the cell walls which the mycelium penetrates, the more plen- 
tiful are the suckers. The cob of a diseased ear Contains numerous ~ 
mycelial threads, penetrating between and through the cells, andis 
a favorable place for microscopic examination. The tips of mycelial — 
threads are quite pointed and firm, which enables them to penetrate — 
cell walls (Plate XIV, Fig. 2). When young the mycelium is so deli- 
o, 
if 
aa 
por i ¢ 
at 15; abe of 
“ io RT, ea ba 2 
* 
+ 
5th 
