1900-1901. | A Mushroom Disease. 183 
1. Mushrooms in which the stalk and cap are fully de- 
veloped, but are twisted and distorted, often appearing 
as if trodden upon. Fig. 3 is from a photograph of 
a clump of six mushrooms, and illustrates this type. 
In this type the stalk often splits open, and remains 
for a time after the cap is completely decayed 
(see fig. 4), 
2. In the second type the stalk and cap develop rather 
feebly at first, and growth soon ceases in the cap, 
but the stalk develops further and becomes con- 
siderably swollen, as in fig. 5. 
3. In the third type the mushrooms are completely hyper- 
trophied, there being no trace of stalk and cap, the 
mushrooms resembling round whitish balls, as shown 
in figs. 6 and 7. 
Although I have indicated three principal types of malformed 
mushrooms, there are a great many intermediate stages, as 
reference to figs. 8, 9, and 10 will show. The first and 
second types are combined in the clump shown in fig. 8. At 
the top is a mushroom belonging to type one, while all the 
others fall under the second category. Again, in fig. 9 the 
second and third types are represented on the left and right 
of the illustration. In fig. 10 there is a combination of all 
the forms. At the back one or two mushrooms of type one 
occur, the remainder of the mass coming into the third group, 
while in the foreground are some belonging to the second 
type. 
In addition to being malformed, all the diseased mush- 
rooms in the bed are covered with a felt-like coat which is at 
first white in colour, and which changes in a week or ten 
days to a dirty white or greyish hue (see fig. 9). Ultimately 
the whole mushroom becomes black and rots away. A very 
pungent odour is evident near beds containing many diseased 
specimens. The spawn when diseased has a very different 
appearance to healthy spawn. Fig. 11 is from a photograph 
of a patch of healthy spawn, and it has a characteristic thread- 
like appearance, preserving a sharp outline; but in fig. 12, 
which is diseased, the outline is not so sharp, the spawn 
being covered with the felt-like coat that is seen on the 
diseased mushrooms. Healthy spawn also forms a dense net- 
