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ment is conclusive of the fact, that, if due care be taken 

 to get quit of the ova of animals and the seeds of minute 

 vegetables from any fluid or other suitable matrix, and 

 at the same time carefully to exclude the further entrance 

 of them through the admitted air, no traces of animal 

 or vegetable life will appear. The presence of mould in 

 such an apparently inexplicable place as the interior of a 

 large cheese, is owing to the exposure of the curd to the 

 air when the cheese was being made, and the consequent 

 deposition upon it of the minute germs of fungi floating 

 around, which afterwards developed themselves when the 

 curd thus impregnated formed the inside of the cheese. 

 It is well known that the exposure of curd for a single 

 day to the atmosphere, will have the effect of producing 

 mouldy cheese. 



Countless millions of the subtle seeds of fungi, in- 

 visible to the naked eye, and light almost as the particles 

 of vapour around them, are continually floating in the 

 air we breathe, or swimming in the water we drink, or 

 lying amid the impalpable dust and sand of the soil, 

 waiting but the combination of a few simple circum- 

 stances, the presence of warmth or moisture, or a suit- 

 able matrix, to display their vital energies, and to burst 

 into full, free, independent life. Hundreds of thousands 

 of the minute germs of the various moulds which ap- 

 proach us in our very houses, and fasten upon different 

 articles of domestic use, might be and often are dancing 

 about in the air-currents of our apartments, though 

 totally invisible to us ; but could we sufficiently magnify 

 them, as a sunbeam darted in at our windows and illu- 

 minated their bodies, they would appear like so many 



