42 Ve ANNUAL REPORT. 
4 
combination. of organic matter with the oxygen of the air. It is in reality 
a kind of slow combustion. I have seen the stump of an old tree which 
gave so much light that it appeared to be actually on fire. Ordinary print 
could be read by it. Spruce and pine logs frequently are covered by a phos- 
phorescent fungus growing underneath the bark. I once saw a log in a raft 
which was plainly visible in a dark night, at a considerable distance. The 
light in all cases is the same, resembling that of the glow worm, or of a 
match rubbed in the dark. 
Of the fungi which by their growth injure growing crops and trees in. 
this country, unfortunately, but little can be said. This branch of botany 
has been so little studied that the field of knowledge is very limited. It 
seems to be pretty well established that rust, smut, &c., may be propogated 
through the seed sown. Care should be taken, for instance, not to sow 
wheat threshed from musty straw, or to plant corn from fields where smut 
was prevalent.’ Rank manures also produce or aggravate rust. There 
seems to be no other way of regulating the matter in these cases. A wet 
season always produces more of these fungi than a dry one. This is true of 
all fungi. There also seems to be close connection between the amount of 
fungi upon grains and grasses and cattle diseases. The year of the cattle 
’ plague in England was one in which more red rust was found than ever 
before. Graziers, however, seem to think that the rust does not injure 
cattle. They all agree in saying that in seasons when ergot is plenty, very 
many cattle slip their young. : 
The potato rot has been studied more carefully than most of this class of 
tungi, but the results are very meager. It is known to be due to a certain 
species of fungi (Peronospora infestans); that it also may be produced from 
diseased seed, and that manuring makes it worse. But no preventive or - 
cure has as yet been devised. 
Of mildew, blight, fireblight, and black knot, still less is known. They 
are being carefully studied by the best botanists of England, and some re- 
sults may be looked for soon. For ordinary blight and mildew, sulphur has 
been successfully used. The fireblight so common to crab apple trees in Min- 
‘nesota is still an unsolved puzzle. A careful study of the branches affected 
fails to show a Single sign of the cause. The fact that it begins at the tip 
and works downward, as well as the fact that root pruning in a measure stops 
it, seems to show that the disease is in the circulation of the tree. Almost 
invariably the roots of affected trees are covered with minute fungi. These 
are upon small roots near the tips. What it is I am not yet able to say. 
The best microscope at my command does not show fungi: in the branches 
killed, or in the sap of the tree. In a late paper is an article recommending 
liquid stable manure for trees affected with any of these diseases. It'is to 
be worked into the soil about the roots freely, and also applied to the trunk 
of the trees. A farmer in Iowa told me that he saved a few fine trees from it 
entirely, by sponging them and watering them with strong soapsuds. Healso 
said that the black kuot upon plum and cherry trees, could be prevented by the 
same treatment. He had a fine plum orchard, of both native and cultivated 
varieties, and it was singularly free from these unsightly knobs. It is well 
known that the spawn of most fungi is destroyed by alkaline substances, 
and it appears that he has made good use of this fact. There is no better 
preparation for the teeth than pure soap and water. It not only removes 
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