THE PRINCIPLES OF BOTANY. 
205 
a mystery as tlie action of some medicines ; but still the fact 
is well known, and we have in our own cucumber-house 
produced mildew on the leaves at pleasure, and with 
equal facility destroyed the parasite by a small dusting of 
sulphur. 
We now come to the discussion of the general facts con- 
nected with moulds. Every one knows the blue mould 
which is so agreeable in a ripened Stilton cheese. House- 
wives, on the contrary, are often annoyed at the mouldiness 
of their jams; while mouldy hay, straw, and corn, is some- 
times rendered too familiar to us. In mouldy hay the dust 
which accompanies its removal will be the myriads of minute 
spores of this fungus. 
It would appear that various forms of mildew and mould 
are found in several cases of disease in animals ; thus Messrs. 
Harley and Brown, in their demonstrations of microscopic 
anatomy, describe the Oidium albicans : — “ The well-known 
thrush fungus is developed on the mucous membrane of 
the mouth, tongue, and oesophagus, in aphtha, as well as 
on the surface of sores and diphtheritic exudations. It 
is a fungus found almost everywhere. It grows equally 
well in aqueous solution of strychnine or oxalic acid as 
in the most benign liquid. Its spores are constantly 
floating about in the atmosphere, and the fungus conse- 
quently springs up wherever it finds a suitable habitat, a 
moderate heat and moisture, in conjunction with the presence 
of animal or vegetable matter, being all that is necessary for 
its development.” It is, however, doubtful whether the 
species, in all these situations, are identical ; and it is still, 
too, a vexed question whether or not they are in any way the 
cause or merely a result of disease, and consequent decay or 
eramacausis. 
In illustration of this subject, we reproduce, in an amended 
form, some woodcuts of fungi in oats, published in the Veteri- 
narian for February, 1862. The cases were reported by Mr. 
Mitchell of six horses having died suddenly, it was believed, 
from poisoning. No poison, however, was found on analysis ; 
but the oats were suspected, and it appears that three feeds of 
the oats then in use given to a horse caused death. • The case 
was investigated by Professors Yarnell and Tuson, and some 
of the suspected oats given by them to a mare at the Boyal 
Veterinary College caused her death. 
The oats, it appears, had a musty odour. 
The seeds on being slightly magnified appeared in some 
instances not only altered in their structure, probably er- 
gotised (c), but they were also covered externally with fun- 
XLIII. 15 
