1900-1901. | A Mushroom Disease. 189 
; soil which gave abundant growth of the fungus before 
the spraying, and there was no sign of the disease. 
3. I also examined the drip-water in the tunnel, and it 
proved to be quite free also. 
The results obtained from these tests lead to the conclusion 
that the disease is stamped out, and that if proper precautions 
are taken it will not reappear. 
DESCRIPTIONS OF FIGURES. 
Plate XVIII., Fig. 1. A collection of healthy mushrooms, comprising the 
_ three stages known to the trade as (#) buttons, (6) cups, and (¢) flats :— 
(a) Very young mushrooms—in the centre. 
t (b) Specimens in which the gills are exposed—on the right. 
_ (ec) Fully developed specimens having a flat cap—on the left. 
Fig. 2. Part of a bed of diseased mushrooms in Scotland Street tunnel. 
There were no healthy specimens on this bed. 
Plate X1X., Fig. 3. Malformed mushrooms belonging to the first type. 
_ Stalk and cap fully developed, but stalk twisted and split open. 
Zz Fig. 4: Other examples of first type. Cap almost lost, stalk split open. 
j Fig. 5. Second type mushrooms, in which development of cap is arrested 
Plate XX., Fig. 6. ! These are all of the third type, there being no 
3 no wig. 7.) trace of differentiation into stalk and cap. 
‘Fig. 8. At the back is one example of the first type, while at the front 
_ are two specimens of the second class. 
_ Plate XXI., Fig. 9, On the left are a few weak mushrooms, some of 
which belong to the second class; others apparently sound, but all con- 
taining the disease. On the right side of the clump are eight forms of 
the third type. 
e Fig. 10. At the back of the clump are a few fully developed but distorted 
examples. In the front are a few of the second class, the remainder 
belonging to the third type. 
Fig. 11. A patch of healthy spawn. Outline sharp. Branches numerous. 
Plate XXII., Fig. 12. A patch of diseased spawn. Outline indistinct. 
Branches fewer in number. ; 
_ Fig. 13. Photomicrograph of section of stalk of diseased mushroom with 
hyphe of Verticilliwm running through the tissue. x 150. 
Fig. 14. Photomicrograph of section of mycelium of mushroom infested 
with hyphe of Verticilliwm. x 100. 
_ Fig. 15a. Conidial filaments of Verticilliwm with developing conidia. 
‘x 325. 
Fig. 15b. Conidia of Verticillium. x 325. 
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