YORKSHIRE VETERINARY MEDICAL SOCIETY. 75 
and wool fibres, a few starch granules, and occasionally a few spores 
of fungi. 
Any morbid sprouting mould, musty fungoid growths upon 
walls, or boards, when acted upon by an increased temperature, 
and the fecundating power of light, are a fruitful source of these 
organic germs, or spores. The smut in wheat is an example; the 
black powder, minute as it is, every granule of it constitutes a 
spore; one square inch of surface would contain little less than 
8,000,000. This parasitic fungus is a species belonging to the 
family from which spores in general emanate. The ergot, or parasite 
on rye, is another instance. There can be no doubt that plants in¬ 
fested by these minute fungi, used as food by animals or inhaled in 
respiration, often cause disease of a serious character. 
Scientific researches bring subtle and mysterious phenomena 
within the pale of our comprehension, and blend them with common 
popular knowledge. Thus we find that Professor Tyndal propounds 
the theory of the dust particles dancing in the sunbeam, and shows its 
dangerous bearings. Eminent physicians propound the doctrine 
of morbid germs, and eminent botanists propound the theory of 
fungus spores. These learned men discourse on the origin of 
putrefaction and spontaneous generation of minute animals, which 
none but microscopists have ever seen, but which nevertheless do 
exist in the air as certain as man exists. As we study and con¬ 
template these things, we feel it is a sure and certain indication of 
the advancement of science, and a great step over the ignorance and 
darkness of past times; still we can, as yet, no more understand 
these floating germs than we can how the perfume of a flower is 
diffused through the air, or how a grain of musk should give off its 
peculiar odour for the space of twenty years, and itself not become 
perceptibly diminished in bulk ; we are equally unable to explain 
why, out of twenty persons breathing a loathsome air, one only will 
breathe in a fatal dose, and nineteen will escape the malarious 
poison. We have all experienced the stench of putrid ditches just 
before rain, when the air becomes charged with moisture, and we 
know how sensible the perfume of flowers becomes during the fall of 
the evening dew ; when the air loaded with the odour from a field of 
beans in blossom, this may be perceived many fields away if you 
happen to be in a line with the wind from the beans. These instances 
are incontrovertible evidence of the essence of the blossom being 
supported and floated in the air and carried by currents of the 
wind. Perhaps you are ready to say, “Oh, yes; but there is all 
the difference in the world between these perfumes and deadly 
poisons; they cannot be communicated through the medium of the 
air.” Now here, again, I would argue my point by illustration : 
Is it not a fact patent to all of us, that occasionally we are visited 
by blasts of wincT sweeping over vast tracts of country, drying up 
the sap and shriveling up the foliage of almost every tree and shrub, 
missing only those in peculiarly sheltered positions ? What is this 
but an acrid poison existing in the air ? If only for an hour we 
see its effect, that is palpable to our senses; but we cannot ascer- 
