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the same medium in Petri-dishes showed a special characteristic, namely, — 
that the creeping mycelium spreads toward the margin fr om the inoculated 
point, forming concentric rings of a dirty or purplish brown color. 
(10) Oat Agar Slant. 
On this medium the causal fungus grew very vigorously and also pro- 
duced numerous pycnospores. At first the white aerial mycelium grew active- 
ly and after a while its color gradually turned more or less yellow. Then the 
fungus produced a cotton-like growth over the whole surface of the medium. 
From the first, the mycelial growth was very thick and in about eighty days 
the comparatively large stromata appeared and numerous pycnospores were 
produced from them as reddish masses. 
( )n tlie same medium, Valsa Mali and Valsa Paulowniae also grew active- 
ly and produced pycnospores. 
(11) Synthetic Solution. 
The synthetic solution, which I used as the cultural medium, has the 
following formula : — 
KH 2 P0 4 0.50 MgS0 4 0.25 
N0 3 NH 4 1.00 FeS0 4 trace 
Cane sugar 5.00 Water 100.00 
The pycnospores, when sown in this cultural medium, germinated readily, 
and after a while, a poor thin growth of the mycelium was formed at the 
bottom of the flask. But the growth was very poor ami it soon died without 
growing up to the surface of the liquid. 
8. Effects of Tannic Acid on the Causal Fungus. 
a. Tannin and its Relationship to the Fungi. 
In nature, the causal fungus grows in the bark w hich contains tannin and 
in artificial cultures its spore production was most rapid and vigorous on 
twigs and bark decoction agar. From my histological studies of the diseased 
